model is designed without any tolerances, use a: PrusaSlicer: Print Settings → Advanced → XY Size Compensation b: Cura: Walls → Horizontal Expansion to tune it according your printer accuracy
You can use buck converter and 12V fan if you want and maybe fan controller to limit its spin if you want to have it less noisy.
do not forget to remove one barely visible short from 12v line on decoy board.
put thin double-sided tape on the bottom of the decoy board to stop it from moving from side to side when in places.