[MadMax]

deadlydane: I think you're getting emotionally attached to a particular implementation for this part. In every particular process using materials, there are best practices to follow and not all fabricators will follow them.

For instance, WE cast the original part in materiel which is not particularly strong probably not paying much attention to thermal processing (annealing or age hardening etc), material quality (contaminants such as graphite or slag), much less part design (sharp corners concentrating stress). A poorly cast airsoft gun part made in cheese metal does not compare to a responsibly cast part made in a good steel without heavy graphite inclusions.

You may not be aware that Armalite receivers start out as rough castings of aluminum. An Armalite receiver starts out as a rough casting which is broached (to receive the magazine) and finished machined to receive the trigger group. Despite being cast, Armalite receivers generally meet the needs for a rugged combat weapon and significantly exceed the needs of chairsofting. The castings coming out of Colt's suppliers are not comparable to the scatstings coming out of WE's shop. There are only two or three suppliers of rough castings supplying the significant appetite for Armalite variants in the US.

The design of the part in question is not well suited to being machined. There are some pretty thin sections which would require 3d machining from billet stock with the center pocket done last. If you have access to 5 axis milling, you could drill all the cross holes before opening up the center pocket. After the shape is finished, you could probably bandsaw off the end, but you'd have to put a CNC shaped plug inside the center and clamp the outside with a shape milled into soft jaws to fly cut finish the rough cut end.

I would figure that it'd take about 15min of machining time per part, 8hrs to make the custom tooling, and 5hrs of CAD/CAM time if you give your machine shop the original part. Most shops wouldn't be very happy with the CAD models provided by most amateurs. Too many poorly knitted surfaces so it's difficult to economize there. Besides, most airsofters don't have a granite plate and a CMM or even a pair of calipers. It's difficult to make an accurate CAD model without some decent gauging tools.

So, figure $120/hr for the machine time [$30] (5 axis is quite a machine!), $70/hr for the tooling and CAD time [$910] for a total of $940. Almost all of your costs are in the CAD/tooling setup costs. Even if you run a billion parts and amortize your tooling, a cost of $30 is high for the machine time and it will be difficult to get lower without financing your own Deckel Maho or even a junky Haas mill.

Or, you can painstakingly mill the thing yourself on a manual mill with multiple setups and some custom jigs made on said mill. Make a single mistake in about a thousand moves done in say 10 Z layers and you have a piece of junk. You might as well take the plunge and make it in steel which doesn't have the same fatigue problems as aluminum.

Don't forget that this is a public forum. You don't own this thread and there are many contributors. Just because you don't like an idea doesn't mean you have to violently object to it. Some players might decide to go with different techniques than you and quashing a discussion that isn't going your way isn't a good way to get a good practical discussion on a public forum.