this was made for this model: https://makerworld.com/en/models/488807#profileId-401865

it can hold up to six shells not including the shells in the barrel

it comes in 2 parts (so it fits on the build plate) that you need to bond together. I used super glue but you could use any bonding method you want. you might be able to just slide the parts together but I don't know if it will hold.