So...
the first attempt was a few months ago. I used a condom and squeezed a bunch of silicone into it, then i used another condom to push in the inside. I thought that maybe filling it with water (all I could find to use at the time) would provide enough pressure to form it into the right shape. it didn't really work. in some spots it was too thick and inflexible, in other spots it was too thin and fragile, and it just didn't work.
The second attempt, i used something that was approximately my flaccid size, maybe a little snug, and I covered it with some stretchy plastic tape I had... lind of like plastic shipping wrap but sticky on the one side. I layered silicone on top of that, and then bound it in another layer of the plastic, with the sticky side out so it wouldn't be in the wet silicone. I made a solid section about an inch long out past the end of the inner mold, and left the top open a bit to help the silicone cure. It fit really well, and I could see that I was on the right track, but the solid end, again, was too rigid to look natural, and the sides were a bit thicker than I wanted.
This time I tried making it without wrapping the outside. I used clear silicone and made the inner jig around the shape I wanted the outside to be and made the whole thing out of a thinner layer. I should have used a solid colour silicone. the clear was too hard to tell if it was on consistently and thick enough. this one was too thin and has some torn spots and holes, and it collapses and kinks over too easily. Ive also realized that it's the size of the end that makes it stay on well. if i make it so it starts off snug and gets wider on the inside that my cock kind of "pops" into it and stays there well. the last one is the same size the whole way along the shaft and it's not as comfortable. it doesnt have that glove-like feeling of the second one.