I had similar problems finding a suitable plug for my bathtub because it was a flat drain. I went through quite a few plugs before I found one that fitted and held water. I reviewed all the plugs on my site:
<
a href="http://www.bathtubplugs.com"
>
Bathtub Plug Reviews
<
/a
>
. I moved away from the standard bathtub plug and went for a tub stopper style plug. :)

I had made some video's. Just made a compilation:
http://www.youtube.com/watch?v...
I hope you don't mind that I did a video you also had done... :-[ It was also meant as an exercise, and I intend to use these short video's when I give presentations (so that it has a common theme).
B.t.w., it was printed for actual use, not just for fun. My dad needed one, so when he visited me we printed one out. 8-)

Btw. I had the idea of making a filter-type version. One where the water is supposed to get away, but the semi-solid goey that you don't want to flush gets stuck in the filter. This picture explains it better than I can:
http://www.issm-iseb.org/b2b/p...

The nice thing about this is that you can throw it away after half a year of use, for hygene-related purposes.

Really wonderful! I've bought an incorrect size in the store several times... Now that would be a problem of the past.
Tagged it household and 'spare parts' too.

JS-Kit ate my earlier comment... but I wanted to say that this sort of wish-it-and-make-it-true everyday application is my favorite Thingiverse success story. :-)