When it comes to mounting electronic devices such as power strips — items that have slots molded in the back or bottom of the plastic shell — you might wonder what kind of screws to use. I have had good results with two kinds: #4 flat-head wood screws and 3mm pan-head machine screws. There are undoubtedly others, but these are the ones that I've used.
Part of the problem is that the molded slots in these devices aren't large enough. A fraction of an inch or a couple millimeters extra diameter would allow a lot more flexibility, and give you a chance to use those random screws that have been piling up in the junk drawer over the years.
I most recently bought some #4 wood screws to mount a power strip, because I was short a 3mm threaded insert. I mounted the power strip onto a 6x12-inch piece of modeller's plywood, and that onto the rungs that encircle the table that needed the power strip. The screws fit the slot like a charm.
Prior to this, I've been using 3mm machine screws along with threaded inserts when putting my devices on wooden objects. The pan heads on these little screws are also the right size to cleanly fit the slots. In one case, I tapped 3mm 0.5 threads on the metal support arms of my TV stand, so I could hang my power strip behind the TV instead of letting it collect dust and cobwebs on the floor. It will still collect dust and cobwebs, but I can vacuum it out more easily.
When measuring for the slots, put a piece of paper over the device and carefully make a rubbing of the slots. Use a center punch to transfer the spacing accurately to the mounting destination. Sometimes a device will come with a pre-printed sheet for this purpose. Double check to make sure the sheet is accurate before you start drilling.
