Step up regulator/ current driver

I'm wanting to power 4 to 8 smd leds off of a 1 cell lipo battery. 3-4.2V. I've found a few step up boost regulators such as this one that has a potentiometer to adjust the output voltage but I'd like for the pot to adjust the output current so that I'd be able to drive the leds anywhere from 5-25mah. I've watched videos on etching a pcb but don't care to do that so is there a manufacturer that I can send me specs to and have a few built for a reasonable cost? It also needs to be as light weight as possible. Thanks in advance.