I was wondering if anybody has made their own?
Are chocks made to hold bike upright without using kickstands?
I haven't made my own (I can't weld), but Harbor Freight puts theirs on sale every so often. I got mine that way.
The basic idea, as you ask, is to hold the front tire immobile and vertical. Once you roll the front tire in there, there's no need for a kickstand.
In more detail, you want a lever of sorts where the weight of the front tire keeps it locked into the chock. Note the pivot point of the bottom cradle in the below images. Should be fairly simple to create one since you know how to weld.

