I looked up the design and specs on one but it looks a little too tricky for me to make. The last time that Midway had the Tap O cap in stock I missed out on it. I wasn't making caps then, but If anyone has a Tap O Cap,, I'd be willing to trade a brick of .22lr for one. If I cant find one I just might come up with a similar, but more simple, easy to use design. I have some Ideas about one to make and if it works out I'll post it, and if I find one I probably won't even bother - thanks for reading-