Jastrow illusion twin trays — 3D-printable model preview

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Desk organisation Medium

Jastrow illusion twin trays

Hold pens in two identical curved trays that seem to change size when swapped

These two curved desk trays are exactly the same size, but nobody will believe it. Laid one above the other, the lower one looks clearly bigger. Swap them over and the other one grows. It is the Jastrow illusion, found in 1889: your eye compares the short inner edge of the top curve with the long outer edge of the one below. Use them for pens and clips, and keep a ruler handy for the arguments.

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Size (Base A): 200 × 89 × 25 mm
Shape: Custom outline
Walls: 2.0 mm
Volume: 93.1 cm³
Est. weight (PLA): 115 g
Parts to print: 1
Category: Desk organisation
Made by: Krypto
Built in: 9 steps

What’s in it

Custom outline, 200 × 89 × 25 mm, with 2.0 mm walls
Custom outline traced from a shape
One more base built on (Base B)
Base B: custom outline, 200 × 89 mm, 25 mm tall (beside)

How to print it

They print as two separate pieces. Lay one curve above the other, then swap them over.

Prints as shown on its outline, no supports.

Filament: at most about 115 g of PLA printed solid (roughly $2.31 at $20 per kg); normal infill uses less.

To get the files, open it in the generator and choose File › Download STL (one file per part) or Download 3MF (every part on one plate).

Questions

What size is the jastrow illusion twin trays model?

The jastrow illusion twin trays model measures 200 × 89 × 25 mm (width × depth × height). That is Base A; one more base is built on. You can change every size in the free SO3D.xyz generator before you download it.

Does it need supports?

No. They print as two separate pieces. Lay one curve above the other, then swap them over. Prints as shown on its outline, no supports.

How much filament does it use?

At most about 115 g of PLA (93.1 cm³ printed solid), roughly $2.31 of filament at $20 per kg. Normal infill uses less.

Can I change it?

Yes. Open it in the SO3D.xyz generator (free, in your browser), change the size, walls, dividers, holes, text or anything else, then download it as STL or 3MF for your slicer.

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Make it fit your space

Change the size, walls, dividers, holes and labels of the jastrow illusion twin trays model in your browser, then download it for your printer. Free, no CAD needed.

Customize this model