I made another attempt to make a proper fleshlight out of corn starch to see if it's a hoax or for real. This time I use a good size cup, a 3" diameter plastic cup from fast food joints, and deep enough for my cock. The proportion of starch to water I don't know because of some confusion. But I did some other experiments after. I put the mixture in microwave and wait for it to boil. When the mixture is solid enough, I insert a plastic stick in the middle and microwave a little more.
When the stuff cooled, like 30 min, I took out the stick. The shape seem to be solid, but it's a bit gluey around the stick. So I waited for it to dry or solidify completely. So it happened I left it overnight.
The next day, the fleshlight is good to hold, and nice to touch. Dry and smooth at the outside and feels soft and moist in the middle. But actually it's dry. The problem is, you can't insert. If you are somewhat bigger than the hole you are out of luck. But if you make it too soft, you are like inserting into a paste and you can expect nothing much will happen.
So even thought the plastic cup is expandable, I cannot expand the hole and insert. So I took the whole fleshlight out of the cup. I managed to insert completely inside
Without the cup, you can't do much about the corn starch. It feels good, but you can't masturbate, can't squeeze. The starch began to disintegrate into pieces.
Here's the experiments I did after. I tried corn starch and potato starch. Corn starch is milky white and tasteless while potato starch is transparent, with a little potato smell and taste. I put the starch mixture into the microwave just for it to boil and then use water cooling on the outside of the container. Using 1 volume of starch to 5 volume of water, both are jelly like, sticky, and you can insert your finger with ease. The jelly do not come off with your finger. Twice that, 2:5 in the potato starch to water ratio, it look similar but you can hardly insert your finger into the starch.
So there's still possibilities. At least breast making is promising.
For the starch, I measure using milk powder scoops which are 20 ml. For water I use half a 200 ml cup. Making large volumes of starch will be somewhat different than making small volumes. Potato starch have the tendency to settle at the bottom, making it harder there. Corn starch is probably more even.