We bought a large tub for our kid, but it didn't have a drain.
_3D printer to the rescue!_
For hygiene, all parts should be watertight. Suggestions:
1. Print with a large amount of walls (side and top/bottom)
2. Overextrude using extrusion multiplier
3. Seal the print later (I used ABS slurry to seal mine).
**Additional required parts:**
1. [silicone toilet flush seal](https://duckduckgo.com/?q=flush+valve+seal+7381042-0070A&atb=v1-1&iar=images&iax=images&ia=images) with a ~25mm (1") ID
2. Some sort of water tight glue to adhere the threaded part to the tub (Silicone caulking recommended)
3. 25mm drill (usually a step drill) to drill through the tub (or a sharp and hot knife to through the tub).
1. Drill a ~25mm through the tub
2. On the male thread: place a modest amount of silicone caulking on the top surface of the large disc
3. insert the threaded part through the hole from the bottom (caulking should now be sandwiched between threaded part and tub bottom
4. Wipe away any excess on the inside of the tub and the outside.
5. Let the caulking set per the manufacturer's directions
6. Place a [silicone toilet flush seal](https://duckduckgo.com/?q=flush+valve+seal+7381042-0070A&atb=v1-1&iar=images&iax=images&ia=images) on the threaded part from the inside
7. Thread nut onto the thread, when tightened it should sandwich the silicone seal and create a tight seal
8. To let water out, partially loosen the nut