You can make hand-held, multi-use, power projectors.
Inventing a Ray Gun requires a Laboratory and fresh materials, the cost of which is PDC 19 + the CP cost of the power. You make any and all choices about the power’s effect at the time when you build it, including ranks, enhancement, limitations, energy or damage types, etc..
The build time of a Ray Gun equals twice the CP cost of its power in hours. Under emergency circumstances (i.e., during a game session), you can spend up to 16 hours a day building a Ray Gun, but under normal circumstances (i.e., “down time” between games), you can work a maximum of 8 hours a day.
To actually build the device requires a Powercraft check. The DC is 10 + the total CP cost of the power you load into the Ray Gun (DC = 10 + CP cost).
Within any given seven-day period, the number of devices you can build is limited by the total CP cost of the powers you load into them. That number cannot exceed your Constitution modifier times ten. For example, if you have Constitution 18 (+4), then you cannot make more than 40CPs worth of devices in one seven-day period.