What to do is roughly layout your Dna parts (battery, board, switches, 510 connector etc) and take some measurements i.e LXWXH in (mm) then go onto Hammond manufacturing website and they have a full list of sizes for all there enclosures, Check the Data sheet and make sure the screw poles don't come in the way and if you will have enough space to fit everything in the enclosure, then you should know what you need