Sports (Tennis) Toss Disc

I don't like to spin my racket at the start of a match (and let it fall to the court, or try to interpret which way is up and down, the usual methods to determine who chooses the starting conditions of the match), so instead designed these discs. To protect the court surface they are designed to fit into a large rubber O ring. I tried various designations on the discs and ended up with U for Up and D for Down being the most favored among the test group, other versions are included for Heads/Tails and Zero/One. Normal procedure is to call it while the disc is spinning in the air and allow it to land on the court. Winner of the toss chooses to serve, receive or select the starting side or whatever is appropriate for the sport.

These have been tested with default print settings using PLA (avoid as it warped on warm days) and PETG which has been good so far. Printed on Prusa MK3, MK4 and XL, not that it matters. ASA or ABS would also be good.

They print without support which causes the underside letter inset to be bridged so it is rougher than the top inset but satisfactory.

You can either do two filament swaps to get the color contrast for the lettering, or print in one color and use a contrasting color marker, paint or filler to make the cut-in letters more visible or just leave them a bit hard to read, as desired.

The holes were added to facilitate clipping to the tennis bag or keyring and symmetric to maintain balance. 

O Ring Size is 327 1 3/4 ID, 2 1/8 OD by 3/16 width inches, or (43.82 ID x 5.33 W mm), Nitrile 70A was satisfactory.

Designed in OpenSCAD.