1:9 Scale Jump Cup
These 1:9 scale jump cups will fit a 3/8" square dowel. The sketchup file is included.
These are small, VERY thin and are relatively delicate! I recommend printing out more than you need, because the quality tends to be variable. I also wouldn't give these to children (bruckj's jump cups here look like they'd be MUCH better for play).
These print best when printed slowly. I have used ABS in the past, and it's worked fine - I don't know if PLA would be even more delicate.
Despite all of these caveats, I've printed and used these successfully at model horse shows :)