My first knee darts were pens. I had some fat ball point clicky pens. The tip was the right size for the pointed part, and when separated, the other half of it had some rings that made it look close enough for a Halloween Fett.
Painting them is not hard... do aluminum first, then your tan (light yellow) with a paint pen. Mask all the parts that should stay tan/aluminum and then spray paint the whole thing. Some people like to do it with the bright yellow rustoleum then mist with reds and oranges to get the right tone. I think if you're trying to do it quick and cheap, Krylon Bauhaus Gold is pretty close.
What's gonna drive you crazy (and you should probably try to do before painting) is making them stay in place. I believe the reference material just calls for a single white elastic strap. How you attach that and whether it can be detached, is up to you. Mine's got the strap attached inside of the outer edge (lots of glue, then stapled thru a piece of sintra, then that sintra glued into the armor for more surface area of glue contact), and a heavy duty snap on the inside edge. The snap i glued on the armor, and it's sewn on to thick canvas end that I put on the elastic. After all that was done to ensure that putting it on isn't going to pop the elastic out, I found they still liked to slide down my leg. I now have little pads (fabric pocket filled with padding) attached to inside the knee with velcro, and that pad has a snap that matches up to the knee of the flightsuit. It took a lot of trial and error to get that snap placed right. Remember, while doing all this, you'll be constantly chipping away at your paintjob. I learned that, then had to sand em back to flat and wrap my elastic, velcro (that's why the pad comes out) and snaps with masking tape so I could basically start over on painting.
