I'll take some photos later, but I'm planning on the positive at the top, 510 end, so I rounded the negative end to get that clearance at the top. The way the sled is built the contacts can be recessed below the plastic at both the top and bottom with a little crimp from a pair of needle nose. Kapton tape is just a little extra insurance in case anything moves/changes. I assume that they relied on the rounded corners of the case up there to improve the friction for the wedge fit, at least that's what I'm planning on so far. Even without wedging it in place the sled needs to be put in and removed almost perfectly parallel so it doesn't jam along the way.