I don't know how many people know this, but if you print a lithopane in TPU on bare glass it makes a pretty good static cling picture

I printed a lithopane in TPU a little over 2 years ago. I was printing TPU on bare clean glass and while removing it from the bed it fell back down and re-adhered so well I though "I wonder if this will stick to the window". So I tried and lo and behold it works just like a static cling decal. It's been on my window/door now for over 2 years and has never fallen off, even when opening closing the door. Just thought I'd let you guys know in case anyone else wanted to give it a try.

A few key points:

• The glass you print on has to be perfectly clean and smooth. I tried with one printed on a thin a layer of glue that looked and felt extremely smooth but it didn't stick at all to the window even after washing away any glue residue.
• Your first layer needs to be perfectly adjusted. Small gaps between the lines on the solid infill will interfere in the suction/static and not hold as well. Adding a slight negative z-offset (-0.02 or so) so the nozzle in effect "over extrudes" a bit on the first layer and no individual lines are visible when it is removed is also recommended.
• You will have to print the lithopane flat and not on end (which wouldn't work well in TPU anyways) so that will reduce the picture quality somewhat.
• I find TPU prints that are no more than a few millimeters thick will stick to bare glass great, but thicker prints tend to lift off so I advise keeping the print 2-3mm thick at the most and probably not put a thick border on the edges.
• My TPU has yellowed a bit over the last few years from sun exposure, but it is not excessive yet.

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TPU lithopane cling