The boots I found were just some wedge boots off of DSW and I slowly but surely cut off the heel.
Then I filled the heel with some of those plastic beads that scale model hobbyists use to replicate water.
Not pictured, I covered the bottom of that with a small bit of fiberglass cloth and resin and put some black plastidip on top to make it look more like the bottom of the boot.
I didn't get it done for yesterday's convention, which is fine. I went without my boots. But I plan on taking my time to spiff them up for the next convention. I had the springs already made for a quick and dirty job, but next I'm going to get some plexi to bend and help support my weight just a little bit. Honestly, it should be able to support some with the method I'll use to attach it to the boot, but obviously not practical or safe enough to just walk around on my heels.
Really as far as weight support goes, so long as you find a shoe where you are sitting more on the ball of your foot, it's not much worse than walking in regular heels. I spent an afternoon walking around in those boots, sans heels, and it wasn't hard. The spring sticking out behind might be a little awkward to get used to, but I know it'll be far easier than the first knee replacement springs from Portal. Those were a PAIN. Literally.
But here is how far I got with covering the front. I'm half tempted to rip this off and start again, it's not nearly as smooth as I would like it, and I do have plenty of pvc vinyl.