Last time I tried to fixed my toilet, and I accidentally lost a part for the piston. I probably flushed it. I had been searching around and also had my friend who worked with kitchenware industry looking for that part, but I had no luck to find it.
Luckily, since I knew that I probably could print the spare part with 3D printer, I had created a 3D model with Sketchup. Also, big thank to Manolis from Dim Sum Labs printed out my replacement part with his 3D printer.
And it worked perfectly!

