Like many bathrooms mine has stupid design flaws. In particular mine has particle board skirting around the "shub" (shower over bath tub). No matter how well painted this material is, water gets in. The particle board then does what it does best, it swells up like a bad allergic reaction!

Instead of replacing it with more of the same I printed some replacement skirting in PETG designed to match my skirting.
I would not try and print this unless you have a removable flexible built plate, It is a large flat surface, you need a good printer, well leveled with a really flat build platform.

Edit the openscad as needed for the lengths and options you need.
See the examples at the bottom of the openscad file.