Spacer for unsupported puzzle pieces of calendar puzzle

In this calendar puzzle, you need to leave the current date open while blocking all other dates with the available puzzle pieces. However, when using the stand to keep the puzzle vertical after solving it, some pieces may be unsupported and fall down.

To solve this, I designed a simple spacer that provides support for otherwise unsupported puzzle pieces, preventing them from falling.

This issue only occurs in very specific solutions where tall pieces are involved.

I printed three spacers, which can be placed in the open slots for the current date when the puzzle is solved.