We have a Bearded Dragon and my wife wanted a larger bathing option for it. I'm still looking for all the reasons to justify the printer so this was a perfect opportunity.
I created it in Fusion 360 and processed in Slic3r. I'm still pretty new to the printing process. I kept the resolution at 0.2 Quality and 20% fill but with 4 top and bottom layers and 4 perimeter walls.
It's about 8 inches by 8 inches and 0.75 tall. Water depth is about 0.5 inch.
Took about 13hrs to print.
On safety and longevity:
Both PLA and PETG plastics are generally considered food safe but some of the dyes and additives might not be.
The bowl will be painted with non-toxic acrylics and coated with plasti-dip (also generally considered safe) to seal the paint.
I recommend printing in PETG long term since PLA is biodegradable and the presence of heat and water will cause it to break down.
Disclaimer: I'm a hobbyist, and everything I've stated is based on personal experience and google search results; I recommend doing your own research and consulting professionals whenever possible.
3D Solutech PETG
I printed extra perimeters and top/bottom layers to help with waterproofing. (4 and 4)
Autodesk Fusion 360 Builder Edition