This triangle is designed so that when painting a wooden board (e.g. a cabinet door) you can paint both sides without waiting for the first side to dry. It is possible to turn over the wood by yourself.

You have to print at least 4 of them.

CAD Model

https://cad.onshape.com/documents/836e7008033d74b6ea1d8eaa/w/1bba981f70857c79dcb05b90/e/3d59920a7ff9f135377f9c0c?renderMode=0&uiState=64ba4452355e3f00db320471