Soldato
Nice neat job.
My way, I decide on height of switch/socket, use level to draw straight line, place dry lining box on the line, draw around the box.
Then run around the edge of the box marking with a Hacking knife or Stanley Knife & straight edge to score plasterboard, then finish off by cutting out opening with pad saw just inside scored line.
Been painting the living room, putting up a new desk in a different place, carpet cleaning ready for my new sofa getting delivered on sat
How's that worked for you? Been considering renting such a device from my local Homebase, as with a baby running around throwing stuff everywhere our carpets are in need of a freshen up.