Where can I source the lost bottom for a removable tart pan?

I also have four tart rings with no bottoms (got them for free from the restaurant I was working in). I used to make bottoms each time out of tin foil, but have since just started using them without a bottom by pushing them off onto a sheet pan and it works fine, though best for tarts where you prebake the shell at least somewhat.

I have also used ereplacementparts.com for blender and juicer parts.

Thanks, everyone, this is very helpful -- including all the ideas about hacking a bottom-less tart pan!!

I think you can probably still use the rings without the bottoms. Since you most likely be lining the pan with a dough, put the rings on top of parchment, in a baking sheet. Line the dough into the rings and blind bake or fill your tart and bake. The baked tart will release from parchment. You don't have to worry about leaking since you have a crust. I've seen chefs bake cakes in round rings, not cake pans (the cake batter is probably very foamy or thick. So I think you can most likely do without the bottoms.

Another solution, if you're short on time, is to use tin foil to shorten a baking sheet. Amanda's solution here is square, but you could also make a circle.

Search in Features:
"Hacking a Tart Pan"
http://food52.com/blog/3500-hacking-a-tart-pan

What a great resource, Monita. Thank you for sharing.

Monita, you have made my day! spare bottoms are impossible to come by so this is just fabulous!

Here's a website that sells just tart pan bottoms
http://cooksdream.com/store/bec.html

Back when I was catering, I lost countless bottoms of tart and springform pans before I got the notion to make false bottoms for them. I have never found a source for "extra bottoms."

Do you know who made the pans?