That is now a very coherent build plan—and 41 × 25.5 inches is a good prototype-panel size if it gives the IR frame a usable outer mounting border. The first thing to confirm is whether that measurement is the glass panel size you want or the actual outside dimensions of the IR frame; either way, making a cardboard/paper outline first will settle it before you buy plastic.
Your build stack
- IR frame on the front of the panel
Attach the existing IR frame to the front face of the clear panel, just as it is currently attached to the TV. The panel becomes its rigid touch surface and carries the frame. IR frames are designed as retrofittable overlays for an existing surface.[1][2] - 41 × 25.5 × 1/8-inch polycarbonate prototype
Buy this first—not glass. Polycarbonate is impact-resistant, easy to drill, and forgiving while you work out where the spider arms go. TAP Plastics at 154 South Van Ness can cut it, with typical cut tolerance around ±1/32 inch; their basic cuts are often same-day.[3][4][5] - Rear structural frame / VESA spider
Make a rectangular rear frame from aluminum flat bar or angle, bolted to the existing outer bolts of the TV’s rear adapter plate. Two side rails travel around the TV edges and forward, supporting the polycarbonate panel at its outer border. This is the load-bearing structure; the TV top cap only steadies and hides things. - Filter cassette behind the IR panel
The rollers, guides, and caps mount to the VESA spider structure, close to the TV. They should be entirely outside the IR frame’s sensing rectangle. - TV + existing VESA adapter plate
The existing plate is the anchor. Do not use the TV’s plastic shell, touch frame, or polycarbonate panel as primary structure.
Find the cassette parts
You do not need springs in either roller for Version 1.
| Part | What to search/buy | Simple first choice |
|---|---|---|
| Top supply roller | “1 inch aluminum tube” or “1 inch PVC conduit” | Your cardboard tube first |
| Bottom take-up roller | Same tube as the top | 1 inch PVC or aluminum tube |
| Axles | “5 mm steel rod” or “¼ inch threaded rod” | ¼-inch threaded rod, washers, Nyloc nuts |
| Roller supports | “¼ inch flange bearing” or “¼ inch nylon bushing” | Nylon bushings in ABS/acrylic end plates |
| Drive | “hand crank shaft knob” | Knob on one end of bottom roller |
| Supply tension | “felt washer” + “wing nut” | Adjustable friction brake on top axle |
| Timing belt, later | “GT2 6 mm timing belt” | Do not fit it for Version 1 |
| “Gears” | You mean timing pulleys | Two 20-tooth GT2 pulleys, matched to axle diameter |
| Filter guides | “black plastic U-channel” or “black edge trim” | Two thin black U-channel strips, lightly felt-lined |
| Top/bottom caps | “black ABS sheet” or 3-inch ABS/PVC drain pipe | ABS sheet bent/folded into shallow boxes |
| End plates | 1/8-inch black ABS or polycarbonate | Two per roller, with axle holes |
| Gel leaders | “black ripstop nylon” or “black blackout fabric” | Black ripstop plus gaffer-tape seams |
For the later belt experiment, buy matched GT2 parts: a GT2 belt has a 2 mm tooth pitch, and a 6 mm belt must use 6 mm-compatible GT2 pulleys. A typical 20-tooth, 5 mm-bore aluminum pulley includes set screws; do not mix GT2 pulleys with MXL belts because the tooth profiles differ.[6][7][8]
Where to buy
Local: plastic and casing
TAP Plastics, 154 South Van Ness is your best first stop. Ask for:
- Clear polycarbonate, 41 × 25.5 × 1/8 inch
- 1/8-inch black ABS sheet for top/bottom caps and roller end plates
- Small black acrylic/ABS strips for prototype side guides
- Optional black polycarbonate or thin acrylic for cosmetic trim
They offer cut-to-size polycarbonate and other sheet plastics, and the SF store provides cut-to-size services.[3][9][10]
Hardware store: structure and rollers
Buy:
- 1-inch PVC electrical conduit or aluminum tube, two pieces about 42 inches long
- Four small metal L-brackets or aluminum angle
- 1/8-inch × 1-inch aluminum flat bar for the spider-frame rails
- ¼-inch threaded rod, washers, Nyloc nuts, wing nuts
- Felt washers, black weatherstrip, black gaffer tape
- Black plastic edge trim / U-channel, if they have it
Bring your measurements and, ideally, a photo of the VESA adapter plate.
Online: precision bits
Use McMaster-Carr, Adafruit, Amazon, RobotShop, or similar for:
- GT2 belt and pulleys
- Flanged bearings
- Shaft collars
- Hand knobs or a small hand crank
- Plastic-friendly screws and standoffs
McMaster sells timing belts and pulleys in widths including 6 mm, with options for flanges and set-screw shaft mounting.[11][12]
Prototype before rollers
Do the project in this order:
- Get the 41 × 25.5 polycarbonate panel and temporarily tape/attach the IR frame to its front.
- Make the VESA spider frame and safely support the panel around its outer border.
- Put your existing ND film flat against the TV, still held with magnets/clamps.
- Test touch behavior, stability, monitor-arm droop, edge access, and glare.
- Add the top and bottom caps as empty cosmetic mockups from cardboard or foam board.
- Only then build rollers and side channels inside the confirmed available space.
That prevents you from designing a beautiful cassette that turns out to collide with the touch panel, the TV vents, or the monitor arm.
Sources [1] How to Choose a Touch Screen Conversion Frame: IR Frame Guide https://electronics.alibaba.com/buyingguides/ir-touch-screen-conversion-frame-guide [2] IR Touch Frame | Custom Infrared Touch Frame 23-100 Inch … https://www.haitouch.com/product/ir-touch-frame/ [3] TAP Plastics: SAN FRANCISCO, CA https://www.tapplastics.com/about/locations/detail/san_francisco_ca [4] Polycarbonate Sheets Cut-to-Size | UV Protected https://www.tapplastics.com/product/plastics/cut_to_size_plastic/polycarbonate_sheets/516 [5] What does TAP do? https://www.tapplastics.com/product_info/videos/play/what_does_tap_do [6] Aluminum GT2 Timing Pulley – 6mm Belt – 20 Tooth – 5mm Bore https://www.adafruit.com/product/1251 [7] Amazon.com: Gt2 Pulley https://www.amazon.com/gt2-pulley/s?k=gt2+pulley [8] GT2 Timing Pulleys & Belts – WestCoast Products https://wcproducts.com/products/gt2-timing-pulleys-belts [9] TAP Plastics: Cut to Size, Polycarbonate & Acrylic Plastics https://www.tapplastics.com/ [10] Order Custom Plastic Sheets Cut to Size Online https://www.tapplastics.com/custom-cut-to-size-plastic-sheets [11] Timing-Belt Pulleys | McMaster-Carr https://www.mcmaster.com/products/timing-belt-pulleys [12] Timing Belts | McMaster-Carr https://www.mcmaster.com/products/timing-belts/ [13] Amazon.com: Gt2 Timing Belt Pulley https://www.amazon.com/gt2-timing-belt-pulley/s?k=gt2+timing+belt+pulley [14] TAP PLASTICS – Updated September 2026 – 44 Photos & … https://www.yelp.com/biz/tap-plastics-san-francisco [15] TAP Plastics: San Francisco, CA https://www.tapplastics.com/about/locations/san_francisco_ca [16] TAP Plastics Store Locations https://www.tapplastics.com/about/locations [17] Plastic Materials on Rolls at TAP Plastics https://www.tapplastics.com/product_info/videos/play/roll_stock
Parts List 1
Perfect. Scavenge in layers, not all at once: first build the structural/touch-panel mock-up, then make the cassette, then hunt the elegant mechanism pieces once you know the actual available depth.
Your best first stop is TAP Plastics, 154 South Van Ness for the 41 × 25.5 × 1/8-inch clear polycarbonate test panel and some black ABS scraps for caps/end plates. They cut material to size and are open weekdays 8:30–5:30 and Saturday 9–5.[1][2]
First scavenger list
Look for:
- Two matching straight tubes, roughly 42 inches long: old blind tubes, thin aluminum tubing, curtain rods, PVC electrical conduit, mailing tubes
- Two small roller-bearing things: old printer rollers, window-shade hardware, skateboard bearings, fidget-spinner bearings, small drawer wheels
- One knob, crank, wing nut, or old appliance handle for the take-up roller
- Black plastic U-channel, edge trim, cable raceway, or even split rubber hose for filter guides
- Black ABS/PVC sheet, thin plastic sign material, or a broken black storage bin for cassette caps/end plates
- Aluminum flat bar, aluminum angle, perforated metal strap, or old shelf brackets for the VESA spider arms
- Black ripstop, blackout curtain fabric, gaffer tape, or webbing for filter leaders between the gel panels
Do not worry about timing belts yet. For the first working cassette, the bottom roller should be hand-driven and the top roller should freewheel with a simple friction brake. The roller geometry—not the belt—is the part to prove first. Timing belt/pulley parts are easy to add later from McMaster, robotics suppliers, or surplus sources.[3][4]
Good local hunting stops
- Center Hardware is a sensible place to browse for the structural oddments: aluminum, fasteners, plumbing/electrical conduit, weatherstrip, knobs, brackets, and paint.[5]
- O’Reilly Auto Parts, 2300 16th St may be unexpectedly useful for rubber edging, small belts, hose, trim clips, black fasteners, and automotive-style material; it is open into the evening.[6]
- HSC Electronic Supply in South San Francisco is worth a surplus pilgrimage for strange mechanical/electronics bits—rollers, shafts, bearings, knobs, pulleys, and one-off enclosures are exactly the sort of thing that can appear there.[7]
- TAP Plastics is your likely source for the clear prototype panel and black plastic casing materials.[1]
Bring a tiny note
Put this in your phone:
Touch panel: 41 × 25.5 in
Clear panel: 1/8-in polycarbonate prototype
Cassette opening: TV image area + ½ in
Rollers: about 42 in long
Structure: connects to existing VESA adapter plate
Goal: ND gel moves vertically, all rollers/guides outside IR-frame opening
That way, when you find a suspiciously perfect tube or piece of channel, you can instantly decide whether it belongs in the pile.
Sources [1] TAP Plastics: SAN FRANCISCO, CA https://www.tapplastics.com/about/locations/detail/san_francisco_ca [2] TAP Plastics – San Francisco, CA https://www.yelp.com/biz/tap-plastics-san-francisco?start=20 [3] Timing Belts, Timing Pulleys, Sprockets and Chains – SDP/SI https://sdp-si.com/products/Timing-Belt-Pulleys/index.php [4] Timing-Belt Pulleys | McMaster-Carr https://www.mcmaster.com/products/timing-belt-pulleys [5] Center Hardware – San Francisco Bay Area's Best & Oldest … https://www.centerhardware.com/ [6] O'Reilly Auto Parts – San Francisco Store #3032 https://locations.oreillyauto.com/en-us/ca/sanfrancisco/autoparts-3032.html [7] Where to buy PIC microcontrollers and other electronic components … https://avtanski.net/projects/local_shops.html [8] San-Francisco California Electronic Component Parts Supplier https://www.elliottelectronicsupply.com/lp/electronic-component-store.php?city=San-Francisco&state=California [9] Unidentified MFG – 14XL – Hardware, timing belt/pulley. https://www.electronicsurplus.com/14xl-hardware-timing-belt-pulley [10] Pulleys & V-Belts – Surplus Center https://surpluscenter.com/pulleys-v-belts/ [11] Unbranded 72 H 100 x SF Timing Belt Pulley / Sheave SF" Bush. Bore. https://www.ebay.com/itm/306740241710 [12] TOP 10 BEST Electronic Parts in San Francisco, CA – (2026 Guide) https://www.yelp.com/search?find_desc=Electronic+Parts&find_loc=San+Francisco,+CA [13] Electronic Parts Stores? : r/sanfrancisco – Reddit https://www.reddit.com/r/sanfrancisco/comments/18djatb/electronic_parts_stores/ [14] TAP PLASTICS – San Francisco CA – Hours, Directions, Reviews – Loc8NearMe https://www.loc8nearme.com/california/san-francisco/tap-plastics/6424184/ [15] Yahoo Local Web Search https://local.yahoo.com/info-21340293-tap-plastics-san-francisco [16] Tap Plastics – 84 Reviews – Hobby Shops in San Francisco, CA … https://reviews.birdeye.com/tap-plastics-148567288191833