To make Dextrin.
I get Corn Starch and spread it out on to a cookie sheet.
I place it in my oven at 400 degrees and watch it closely.
You want the corn starch to Start Toasting on top.
Then mix it up with a fork and spatula.
Then let it toast some more.
Do this a couple of times untill all the corn starch is Golden Brown but not burnt.
Or you can just order Dextrin on line from pyrotechnic suppliers.
Just the shipping costs will be double what a can of corn starch will cost you at a grocery store.
I have also toasted Dextrin in a cast iron skillet on the stove.