Thanks to this tutorial I decided to refresh my TF9 inline skates in hopes it'll get me to play more roller this spring/summer. New Marsblade O2 insert, new 3D printed True tongues, and carbon-look kydex 'shot blockers' around the backs to protect the heel. The Kydex and 3M tape cost a whopping $20 total so this was a cheap project to try. I even have enough material left over to make another pair.
Using a jigsaw would have allowed more precision and cleaner lines, but a Dremel is what I had on hand and it worked easily enough. After cutting I sanded/beveled the edges, then used a heat gun to shape the material. Once each heel was roughly curved, I put on the 3M tape, applied more heat so the kydex was soft like play-doh, and with an oven mitt on my free hand, was able to press/conform the material to fit the odd shape of True heels pretty much perfect. If I were to do it again, I'd create a cleaner template so each piece would be identical, but whatever.
Thanks again for the tips in this thread!