Do yourself a favour, go down to a Home Despot or Lowes nd gt yorself a length of abs pipe in the diameter you want.
Slice it up into rings. It'll cut with a hacksaw or any table saw blade Now, clean them up and get some dough and try lining the suckers out.
I Insist on you doing this, O.K.?
It's a right royal pain in the arse. With a "proper" tart pan, the bottom is included, so you can pop in a disc of dough, press it into the corners, and use your thumbs to trim off. With pipe slices, you have no bottom, so the ring has to be constantly on the sheet pan, and when it shifts around, the dough shifts with it, ruining your work. And, because the walls of a ring are perfectly vertical, it will be very frustrating--if not impossible--to bake the tart blind, which you will need to do for maybe 50% of your tarts.. I believe I said this in my above post.
Yes the rings are cheaper, but your labour to accommodate lining a ring with dough will be 8-10 times MORE than with a "proper" tart form.
You can use the abs rings for indv. cheesecake-lets (wrap it in 2 layers of alum foil when you poach them)
You can use metal rings for cakes and other desserts, but for tarts, it will be a right royal pain in the arse.
You money, your time, your labour, your choice.
I've been there and done it,and my advice is free.
Just consider it, O.K.?