We do a lot of printwork for Nike in Asia. Not sure if the stretch fabric is handled the same way but the tees we make there are done with an adhesive sheet that works like a foil application.
A water based glue is print/flash/printed through an open mesh 3 to 5 times. Then these pieces have the transfer sheets applied and are heat pressed much like foiling is done.
This produces a far superior effect than reflective ink because each glass bead falls correctly on the paper and is therefore in an optimal position to reflect maximum light when applied to the fabric.
These sheets are expensive even in China, the only thing we have found that MAY work similarly are transfer sheets from Optilux, we haven't tested them this way yet. Very cost prohibitive.
Best of luck.
