Obsolete-spares scouting · revised filter · prices checked on ebay.at, Sept 2026

Twelve Parts Worth Copying

Second pass, with gears thrown out. The first list drifted into gearing because the incumbent seller I found sells gears — but gears are the worst thing a printer can make: meshing surfaces, cyclic load, and buyers who’ve been burned. These are parts shaped like that PLC key instead. Geometry, not mechanism.

The filter, restated

Nothing that meshes or slides

No teeth, no bearing surfaces, no sealing faces. A part that only has to fit forgives a tenth of a millimetre; a part that has to run does not. This is what makes the key a good subject and a gear a bad one.

Fails by loss, cracking or UV — not wear

If the original died from abrasion, yours will too, faster. Look for parts that snap, get brittle, discolour, or simply go missing. Those failures a print survives indefinitely.

Static parts have their own proof

3dfactor (Hungary, 10K feedback) sells printed roof-bar end caps at €8–22. Same model as the gear sellers, none of the mechanical risk. The category works.

Verdict key Build room to enter now Watch viable, but contested or unproven Skip already served

Group A — open ground

Verified prices, no reproduction competition, and geometry a resin printer handles without argument.

01Build

Discontinued appliance control knobs Miele 3917683 / 1574481 / 6740412 · AEG 8996613042713 · oven, hob, range

The closest thing on this list to the key itself. A knob is a shell with a D-shaft socket — no load path, no wear surface, nothing to align. They crack, discolour, and get lost, and an owner with a working €2,000 oven will not scrap it over one. Every listing I found is original or salvaged stock from German parts dealers; nobody is reproducing them.

Market price
€20,00–31,97 each · €99,90 for a 6-knob set
Original
Dealer stock only; discontinued lines already selling used at €20,85
Sourcing
Easy — buy one knob as the reference sample
Catch
Finish and printed markings have to look right at arm’s length. That’s the whole job here
02Build

Discontinued sanitary trim caps and levers Grohe Europlus 02693L00 · Chiara 46230000 · Moen cover caps

Dealers are literally listing these as “Rarität”. Pure cosmetic geometry over a cartridge that’s still fine — the mixer works, the cap has gone brittle, and the alternative is retiling the bathroom. Highest ceiling on the list: one Europlus handle sits at €99,99.

Market price
€30,00 used cap · €38,60 · €49,00 “Rarität” · €99,99 handle
Original
Out of production; sellers are clearing old stock
Sourcing
Buy a used one — they’re listed as samples already
Catch
Chrome is hard to fake. Target the white and coloured variants, not the chrome
03Build

Vintage film-camera battery doors and covers Canon AL-1 · A-series · Minolta · Olympus OM · 1970s–80s bodies

A hinged lid with a coin slot: no tolerance demands at all. One German seller gets €44,85 for a Canon AL-1 door with light seal. The contrast is the proof — modern DSLR doors are commodity at €9–13 because the volume justified tooling; the film-era ones never will.

Market price
€44,85 (vintage) vs €9,90–13,90 (modern DSLR, saturated)
Original
None. Donor bodies only
Sourcing
Broken film bodies are cheap and everywhere
Catch
Battery contacts and the seal are separate parts to source
04Build

Retro computer cosmetic parts Amiga 500 dust cover · Commodore SX-64 trim panels · C64 feet, port covers, badges

Every listing I found was used salvage — €22,95 for a plastic dust flap, €24,95 for a trim strip. Nobody reproduces them. Purely decorative, zero mechanical duty, and a hobby whose participants are middle-aged with disposable income and a restoration already half finished.

Market price
€22,95–26,95 · all used, no new-made stock at all
Original
Commodore gone since 1994. Donor machines only
Sourcing
Good; the retro scene in Vienna is active
Catch
Colour-matching aged beige is genuinely hard, and buyers will notice
05Build

Roof-bar and roof-box end caps Menabo · Thule · Atera · Kamei — discontinued generations

The category that proves the thesis. 3dfactor already sells printed Menabo caps at €8,09–21,99 on 10K feedback. They lift off on the motorway or crack in UV, the bars are otherwise fine, and there are dozens of discontinued rack generations nobody has covered.

Market price
€4,99–21,99 · printed versions already selling
Original
Discontinued per generation; makers only stock current lines
Sourcing
Easy — second-hand racks are cheap
Catch
UV-stable material matters; a part that yellows in one summer earns returns

Group B — proven volume, contested

Sold counts here run into the hundreds, which removes all doubt about demand. The question is whether you can enter against sellers who already have the shelf.

06Build

Fridge door bins, bottle holders and shelf brackets Liebherr 9031106 / 7422888 · Bosch-Siemens 00704760 / 00743239 · AEG 2092504055

The highest verified volume anywhere in this research: 489, 490, 321, 80, 62, 48 and 41 sold across individual listings, at €18,59–74,27 for moulded plastic. Nothing bears load beyond a few bottles, nothing wears. All original stock — no reproduction competition at all.

Market price
€18,59–74,27 · sold counts up to 490 on one listing
Original
Available for current models; discontinued ones are the opening
Sourcing
Easy, but you need the exact model generation
Catch
A full door bin is 40 cm of print. Start with the small brackets and bottle holders
07Build

Velux catches and strike plates GGL / GGU · Putzriegel · Schließblech 025116 T-G2

Carried over from the first list because it passes the new filter cleanly — and because of one number. The plain strike plate sells for €3,99; a reinforced version of the same part sells for €14,99. The market pays 3.7× for a fix rather than a copy.

Market price
€3,99 plain vs €14,99 reinforced · 150+ and 64+ sold
Original
Available — and it’s the part that breaks
Sourcing
Trivial; buy the OEM part itself
Catch
German aftermarket is established. The angle is better, never cheaper
08Watch

Interior trim clips and sun-visor holders Skoda / VW / Volvo · Mercedes W210 visor covers

Textbook static parts — 230 and 111 sold at €6,59–20,49. But German aftermarket houses (YOU.S, alot-performance) injection-mould these by the thousand, and a printer cannot beat a mould on either cost or finish at this price. Listed as the boundary case: right shape, wrong economics.

Market price
€6,59–20,49 · 230 and 111 sold
Original
Widely available, OEM and aftermarket
Sourcing
Trivial
Catch
Only worth it for models too rare to have been moulded for
09Watch

Classic-car vent grilles and louvres Mercedes W124 A1248300754 — and the models nobody moulds for

W124 grilles move at €23,99–43,99 with 193 and 57 sold, which shows what the part is worth. But LST and YOU.S already mould them, so the popular chassis are closed. The opportunity is the same part on cars whose numbers never justified a mould.

Market price
€23,99–43,99 · 193 and 57 sold (W124)
Original
Aftermarket moulded for popular chassis; nothing for the rest
Sourcing
Scrapyards; louvre slats are fiddly to measure
Catch
Pick the chassis first. On a W124 you’ve already lost

Group C — leads, not findings

These fit the filter and I found no one serving them — but I confirmed the absence of supply, not the presence of demand. Test before spending.

10Watch

Eumig projector static parts Mark S · 800 series · reel arms, lens covers, feet, control knobs

Carried over from the first list but reframed: the knobs, covers, reel arms and feet, not the drive train. A Vienna-built brand, dead since 1981, whose machines surface constantly in local estate sales. Searches return zero results of any kind.

Market price
Unpriced — no listings exist to benchmark
Original
Donor machines only
Sourcing
Excellent locally — the reason it stays on the list
Catch
Zero listings can mean zero demand. Check the collector forums first
11Watch

Vintage audio cosmetics from the brands nobody covers Revox · Uher · Braun · Saba · Wega — knobs, buttons, badges, feet

Also reframed away from gears. The Polish sellers cover Philips, Technics, Sony and Grundig internals thoroughly and these brands not at all — and a button cap carries none of a gear’s risk. Restorers pay for cosmetics because that’s what a restoration is judged on.

Market price
Not individually benchmarked — treat as a lead
Original
None. Donor units only
Sourcing
Vienna flea markets and Willhaben
Catch
Braun in particular is design-protected and actively licensed. Check before listing
12Watch

Industrial keys and keycaps beyond Allen-Bradley Siemens Simatic · GE Fanuc · Mitsubishi · panel key switches

The original idea, minus the one part that’s already saturated. Keys are the ideal shape — static, loose-fitting, no wear — and the buyer is a plant with downtime costs, not a consumer. The Allen-Bradley number is taken at €28,91; the others may not be.

Market price
€28,91 for the saturated AB part; others unchecked
Original
Varies by maker — check each part number individually
Sourcing
Hard without insider access. This was the video’s real advantage
Catch
Changes machine state on industrial plant. Heaviest liability on the list

Checked and rejected

Including everything from the first version that the revised filter throws out.

PartMarket priceWhy not
All replacement gears€9–40Meshing teeth, cyclic load, wear. A rival seller advertises “Nicht 3D-Druck” as a feature — the market already distrusts printed gears
Allen-Bradley PLC key 1747-KY1€28,91The video’s own part. Two Chinese sellers already undercut his $50 plan
Lewmar hatch handle kit 361680990€67,68–77,99Eight-plus sellers on one part number. Fully colonised
Tektronix scope knobs and switch caps€3,73–11,88Right shape, wrong market — commodity from China, no margin
Dometic fridge hinges and latches€11,89–31,24Caravan parts look scarce but every number is already knocked off
Roller-shutter end caps€4,99–9,99Correct shape, price too low to cover print time
Garage and gate drive gears€35–189Best pricing found, but load-bearing and safety-relevant. Dropped under the new filter
Märklin locomotive parts€1,50–12,90Salvage sellers dominate; prices too low to model against

Cheapest way to test one

  1. Start with the oven knob. Sample costs one part, the geometry is a weekend, the failure mode is cosmetic, and €20–32 a unit is real money for something that small.
  2. List before you print. One listing, a photo of the original, a two-week lead time. Watchers and questions tell you what a batch of 400 can’t un-tell you.
  3. Solve finish, not strength. On static parts nothing breaks — they get rejected for looking printed. Layer lines, colour match and surface sheen are the entire product.
  4. Cost the finishing honestly. He was blindsided by de-supporting and sanding one part at a time. That is the real per-unit cost, not the resin.
  5. Only then batch. Five sold against five hundred printed is the actual lesson of that video.