This is a 3/8 inch by 2 inch bolt with a hand tightening nut plus a washer. The set contains all parts in one print and each one separately.
I strongly suggest you print the bolt with 2.5mm walls and a triangle infill. If the washer is too tall for your toilet seat then scale the z axis down by 50%.
I deliberately made the threads fairly tight because I never want this to loosen every two weeks like ones you get in the store. I had to first thread the nut backwards to get it to turn correctly and its working perfectly now.
The pictures below have the broken one on the left and my printed one on the right.
| Bolt_-_Toilet_Seat.stl | 7.4MB | |
| Nut_-_Toilet_Seat.stl | 6.8MB | |
| Toilet_Seat_Set.stl | 2.7MB | |
| Washer_-_Toilet_Seat.stl | 171.2KB |
