Hi, I'm building an electric guitar and I want to know how to route out the cavaties for the pickups (humbuckers) , the switch and volume/tone knobs. I don't have any specialist tools, but I do have an electric drill and a jigsaw. I've seen people on the internet do it roughly with a drill then smooth out the edges but in not 100% sure how to this. Any advice on what to do with this equipment would help.

Use a forstner bit to get rid of most of the material:

Then use a router with a guided cutter and template:

(Invalid img)

If you're going to build guitars, you really need to buy a router.
Unfortunately not. Just bite the bullet and buy a router. You can get loads of 1/4" collet routers really cheap.
Where would you reccomend buying one cheap, but is not gunna break as soon as I use it ( I live in the UK)