I tried to order some spare parts from the manufacturer (Tiivi), but they said they don't have any anymore. Here's my faximile of the original part. Seems to work.

It was a bit of a pain to get printed, either due to something going wrong with my printer or my filament, or just me not figuring out how to do it. Eventually I just printed it on the side, which means quite bit of manual cleanup but at least it works.

Optimally one would print them the pointy bit down so minimal support material would be required and all the surfaces would be smooth(er).

Regardless, I'm posting this here in the unlikely case that someone needs a spare part (or dozen) in the future.