a good jig makes it relatively easy, but those are also expensive. good luck getting your hands on a used one at the moment, unless you know someone with one.
when i did mine (last year) went to a friends and used his router jig.
that one was very reusable, and very user friendly. compatible with poly and aluminum. we were able to mill ar15, ar-9 and ar308's on it. they cut very nice lowers too.
takes just under an hour ish to complete a lower with the system he had. poly lowers maybe 35-45 mins (you can use a little deeper cut depth safely). he said it took him another hour+ to get it all assembled when he got it.
this is what he had, run off a dewalt variable speed router. so current market pricing you'll be $450-$500 to get setup this way, possibly more if you dont already have a bench vise.
https://www.5dtactical.com/products/the-router-jig-pro-multiplatform-ar-15-ar-9-ar-45-308-ar-10/
fwiw - this thing f*#$ing throws chips *EVERYWHERE* - even with the vac attachment going. seriously like 3+ feet. nature of the beast, you're milling aluminum, but making sure you know what you're getting into and all that. at the very least you're gonna want full eye and basic(or better) ear protection while using - if your space is comfortable enough, a full face shield would be extra nice.
i recommend making some kind of back stop to work in to keep the chips to a minimal area. even something as simple as a few pieces of cardboard setup in a V around your vise would work to help contain things.
the good thing is - with the market the way it is due to the upcoming rule change, these jigs are a real hot seller right now, so you could buy one and probably at the worst break even once the 80% regs hit here in the tail end of august. might even be able to make a few $ if demand gets super tight mid august for someone desperate.
good luck and have fun!