So now I figured out that you have to fuse the dichro to the background glass before you cap it. Here’s what I also found–when you have iridescent glass in the background, the dichro doesn’t fuse completely flat. That means that even when you fuse it before capping it, you get blisters of air trapped in there.
But I had a new plan. I decided that having legs behind the bodies wasn’t good enough. I also wanted to have some details on top of the bodies, stripes and thorax lines. So after they’d been fused, I put masking tape over it and cut out the mask for the legs and antennae, so I could have gold lines on top of the bodies. Here’s the result.