I LOVE DOING STUFF IN CRAYON SO I'M DOING PWYW SLOTS FOR THESE
Basically there are three sizes which correspond with the amount of minute details I can put in them: Mini, regular, and deluxe. The level of completeness and amount of work I put into the shading depends on how much you pay, obviously.
The mini (left example) requires a minimum of $1, whereas the other two require a minimum of $7.
If you're interested, either note me or comment on this journal