I'm about to shape out my knee pads out of plastic. As for the darts i'm going to get some darts and cut them down then i'll take out the needle then i have darts for my knee pads but not fully in accuracy but they'll do my suits my custom mandalorian after all.
I'm making most of my armor out of PVC plastic its sort of like sintra practically is but in a form of a bucket. I followed the budget armor material idea from a topic i once saw around here.
I did it the hard way...lol.........I made a clay sculpt on a flat sintra knee shape,then molded it in r.t.v.(room temp. vulcanising)silicone,and now I have more knee blocks than God...........lol.....and they simply screw onto the kneepads.
I'm in the middle of molding the whole thing,with kneeblocks already on the main cast,and then add the darts.
I'm very well set up for this kind of thing,but I know most folks aren't,so it's a case of "whatever works,works".
I know I had a hard time with the knees,trying to use any "found" objects for the blocks,so in the end I just bit the bullet,and sculpted it up.
BTW.here's a tip.........attach your darts with springs........zip to the h/ware store(a well stocked one!)and buy a long spring to cut down,or shorter springs.
Glue one end into the knee blocks,and one end to a hole in the darts...........We use the same technique with jet pack missiles.........So,when you get knocked or bumped..."Boing",is what you hear,not "snap"!