This cross- & line laser could be useful for both big and small projects. No need to look for a power outlet, since it runs on batteries. Just get at it!
From Amazon
Bosch Professional Laser Level GLL 2-15 G (green Laser, Interior, LB 10 Mount, Visible Working Range: Up To 15m, 4x AA Battery, In Cardboard Box)
Conrad Electronic
Bosch Professional GLL 2-15 G & Tripod Multi-line laser Incl. bag, Incl. tripod Range (max.): 15 m