If you want to make a similar thing, just mix cornstarch and the cheapest silicone caulk - the one that smells like vinegar.
You can experiment with more or less starch filling, but 50/50 by volume is just the right mixture.
After you mix it you mould it with wet hands.
This mixture, after kneaded a little bit with wet hands will harden across the entire cross-section relatively quickly - unlike pure silicone caulk that hardens from outside in, and 1 inch cross-section would take over a week.
It doesn’t work with the neutral silicone sealant.
Please note, the above recipe is probably not as good as Suguru, but if you buy starch wholesale (like 4 pound bag at once), you can’t beat the price. And you made it yourself 
Recently I have purchased some fancy “construction” glue (some MS polymer, whatever that means), 290ml for 10Eur, and I am going to experiment with starch again.
