okay... this has no real basis beyond my own meandering experiences,
but reading the back of Hammer gel indicates longchain maltodextrins to be used....
I wonder if these are of the same beginnings as the malt syrup one buys in gallon tubs for maybe $10 each for home beer brewing? Could one then, theoretically, take this malt syrup (not as sweet as you'd think...) and mix in fruit juice concentrates and other ingredients found in Hammer etc gels to make a gel themselves?

Also:
for gel with caffiene, would it be possible to heat and dissolve nodoz into it? That sounds significantly more risky than malt syrup and fruit juices, but some people really need their kick... =P