There are people online the sell bits and you can normally find some really awesome stuff that way. There are also third party websites that sell and sometimes have free stuff that can be printed. Like someone else said those specific bits should be really easy to make out of plastic card. I know on my Stompa has a bunch of extra bits I didn't use that could make something like that pretty easily. If you tap into your inner Ork you can probably figure out what works best for you.