Knee Darts and Other Aluminium Parts

For the knee darts, does the 501 only approve machined pieces or is there a way to make them with off the shelf components?

I guess this question also applies to other aluminium pieces such as the gauntlet pieces (darts, missile, flame thrower ect), jet pack, and the toe spikes.

For 501st approval you don't have to have machined parts. That is not a requirement. The requirement is that it has to match visual references. You can scratch build pretty much any part of the costume & pieces, this may not be the most accurate method but may be a more economical route to take if you don't mind taking the time to make things. If you do some looking here there are many threads showing with a little creativity & time what you can accomplish.

Here is what I did on my ROTJ Boba Fett build for the knee darts.

http://www.thedentedhelmet.com/f20/rotj-boba-fett-wip-501st-approved-48239-post612273/#post612273

People do metal knee darts and gauntlet darts honestly for durability reasons. You could make it out of other materials, but I know they get more dinged walking around than just about any other part because of how they stick out.

Good question. Good to know for future reference