sorry for the late reply, i lost connection for a few days.
any structure would work, as long as i know the method, a simple 8x8 color would suffice. it doesn't need shadow, it's just the top pattern.
Viewing post in Sidescroller Tile Set Maker comments
So, it's been a while, I'm sorry and I think I got a solution for your problem.
I've been working on another new tool that can make any kind of circle or ellipse shape, since the shape you send me above wasn't actually a half-circle (and I wasn't sure if that was intended or not).
You can find Circle Shape Maker here, for now it's restricted because I'm not done with the page yet, but the tool should work fine. The password is "circle".
Happy using, hope this is what you're after!