I only made about 100 because I wanted to make sure that I like them. I definitely do like these and I will be making the rest of my slugs exactly like this. Sorry about how dark the picture turned out but here is a close up. They use green felt tips from McMaster, #6 washers, and beige foam from best materials. I highly recommend using these three materials because they are very nice and fairly cheap. Using the felt pads from McMaster also lets you make slugs very quickly. Not only that but the beige foam doesn't melt even if you use a high temp glue gun. The beige foam also has a push fit in cpvc and a great fit in petg.
Here is a picture comparing an old slug with a new one. For the old one I used Frost King; a foam which has terrible fit in everything and melts with high temp hot glue. I also used #8 washers and craft foam.
My final word of advice is to spend some extra money on your darts and it will pay off.