If you’ve ever had the problem of a laptop (especially a slick aluminum MacBook) not staying on your lap, do yourself a favor and buy a roll of CatTongue Grips. 

It’s the first thing I put on a new laptop (well other than critical software) 

I know, I know. Ergonomically we shouldn’t work with a laptop longterm. It’s bad for the shoulders and neck. That’s why I alternate between a laptop stand at a desk and kicking it back on a reclining chair. 

This tape is fantastic. On the one side it’s rubbery (but doesn’t leave any residude on your clothes), and it stays pretty well stuck to the metal of the laptop. A side benefit is it’s easier to hold onto the slab of metal when you’re slinging it into a bag.