My I used up my potato starch. I tried corn starch properly, and the properties was indeed different.
I used 3.7 to 1, water to corn starch ratio by volume. It is the standard corn starch from supermarkets. I used cold water as stirring in hot water is very uneven. I boil the water in the microwave after.
The fleshlight cracked when I removed the PVC pipe in the middle. Corn in more brittle than potato starch. The feeling is good. But the fleshlight kept splitting into pieces.
Potato starch remains sticky even when splitting up into pieces, and the paste is very good for a thick and satisfying lubrication. Corn starch isn't as sticky, and so more easily broken into pieces.
I'm going to make paste the traditional way, simmering in the stove.