You might look into several of the 2000 series aluminums - some of them machine much better than 6061 and have good properties. You have to ballance corrosion and strength and cost.<br><br>CNC machining (especially a lathe!) from bar stock is hard to beat for several hundred units. Castings etc all have some accuracy and consistancy concerns - you have to prove each is ok, but with bar stock, you do your material proof once per bar... Of course each finished part either way will be penetrant inspected if it flys.<br><br>For THOUSANDS of parts, you've got options, because then you can afford the high quality (and cost) tooling that will produce good parts that are accurate and don't require much secondary machining.<br><br>It's flying - how cheap do you want to get??? 500mph 8 miles up.... Big smoking holes...<br>