Small Puzzle

A very simple puzzle concept; Print one base and any set of pieces. Pieces are rated with a difficulty rating from 1-10
Level 1 should take no more than a minute to solve, while level 10 will usually take more than 30 minutes.
This model is easily scalable, but to upscale it, please leave a comment so that I can make a version with tighter tolerances. THE PIECES WILL FIT VERY LOOSE. You will never have to force the pieces.
~1mm of clearance between pieces

(3rd group of pieces is my personal favorite)