Sewing machine feet shelf for Ikea Skådis pegboard

I really liked the original design, but it wouldn't fit my partner's sewing machine (of a different model). Also, one of the feet she had for her machine was too wide to fit in the tray.

Rather than remixing a different tray, she preferred to have a small shelf attachment for the pegboard on her desk, so I re-created this model, using the original STL as inspiration. The middle row of recesses is a little bit wider to accept the blindhem foot that came with her machine.

There's something in the .scad file that triggers a problem in OpenSCAD ( using 2019.01 or a recent nightly) causing the F6 render to fail. Flushing the caches (Design -> Flush caches) helps in this case.