Quick experiment to make a ball maze based on the beloved Benchy - prototype printed in transparent PLA for "debugging", if you want a challenge print it in something opaque. Works well for 6mm / ¼" marbels or ball bearings balls - ball goes in the chimney and pops out the Stern. Scale for larger balls.
Can be printed without support but make sure the first top layer dosn't go horizontal - bottom bridges can be a bit long in that case. And make sure your printer dosn't create strings - you won't be able to get them out once its done.
If interesst is there I might update the version to better include the “anchor hole”.