Adjustable checkpoints for small RC cars or slotcar racing. The inner width is between ~13cm and ~22cm. It uses my tyre stacks as stands.
The connector piece comes in three versions: blank, text "checkpoint" and german text "Fährste quer, siehste mehr" which roughly translates to "drive sideways, see more" ;).
For one checkpoint you need two tyre stacks, two posts and one connector.
Simple prints. The connector needs a few mm of bridging but it should work properly.