Print two halves of upper. MEK together, make sure the holes line up in a lower. Single shot lower included but will work on any AR-15 lower. Acquire metal FCG (Printed disconnector works). Put FCG into lower, you do not need mag release etc. Give barrel an acetone vapor treatment. Load barrel by inserting round in back, inserting into upper, twist 45 degrees for a lock. Roofing nail into firing pin hole, make sure it lines up with the hammer.
##### Note
Always check legality in your area, this would be considered a HANDGUN. For U.S. residents, you do not need to worry about the UFA with metal lowers. Plastic lowers is also probably not an issue as the FCG is all metal (however, be aware).
