For a non anodized lower - raw aluminum - im lead to beleive that due to vagueness in the law anodizing shops wont touch any kind of firearm especially 80%.  

Home type 2 sounds like a pita and expensize.

Alumahyde seems ... viable.. if it was ever in stock.

Wheeler cerama coat.. seems similar

Other options?

KG Gun Kote.

https://www.ar15.com/forums/Armory/Refinishing/19/

Alumahyde 2 is in stock on amazon, and I can confirm it does really well on 80% lowers as long as you follow the prep correctly.

+1 for alumi hyde II , matte black is always on back order , if you cant wait you can pay $10 more on Amazon , also if there are multiple things you may want to spray get them all ready at the same time , after the first use the tip is done and will spit drops/splatter , you can buy like 40 new caps/nozzles on amazon for $5 though

I have found that Alumahyde is a very thick coating.

I prefer Duracoat aerosol for painting aluminum, even though it is more expensive.

Another vote for Alumihyde.  As mentioned, surface prep is critical for good results.

I lightly media blast the surface to remove any oxid.  This also creates a porous surface for paint to adhere.  A white or light grey scotch brite pad can be used if you don't have a media cabinet.  Then I rinse in Isopropyl Alchohol (IPA) and blow dry with compressed air to degrease.  IPA evaporates quickly so an air duster can be used if you don't have a compressor.  Wear gloves the whole time to not impart any new oils from your fingers onto the part.  Then paint.  It's easy to go too thick with Alumihyde so try and limit the number of passes you make over any given area.

With lowers, I start with the interior since you'll naturally get some paint on the exterior surfaces when doing the inside.  Go light as not EVERY millimeter of the interior needs to be perfectly covered.  Then you just need a couple light passes on the exterior to finish up.  Doing the outside first results in over spraying the exterior when you go to do the interior.

Use a long 1/4" screw in the pistol grip hole as a handle to hold when spraying.  You can also wrap a piece of wire around the end of the screw and make a hook to hang it for curing.  An oven can be used to speed up cure time.

I can attest that the finish is very durable.

Good luck.

This is the best thing for a DIY with no tools. Regular ol paint works fine too.

automotive self-etching aluminum primer spray followed by engine enamel spray?

Great info, thanks!