Voltage only boost buck?

[Fitsbain]

I'm looking for something (think sandwich shop boards) that will give me a constant voltage of 3v (+- 0.5 adjustable), from an input of 2 - 4.8 (of course more is better). Don't really want constant current, though a settable upper current limit is ok.

Deal is it will sit on the battery, and be connect to leds, a laser, or nothing by the 3 position switch.

To be run from a protected 18650, or 3xaaa in a holder.

Please help me!!!!

Thanks