Why make one. I brought a frankford arsenal tumbler from reloading solutions for under £40 ( while stocks last ) have a look on there web site
Cheers gaz
The best way to kill em is to strimmer or hedge cut to the ground or as low as *** , let them reshoot to about 6 - 9" then spray with a selective spray ( Garlon 2 or Grazon 90 ) job done
Always use a bore snake after every outing even if I don't have a shot ,if nothing else to pull any moisture out ,then use forest foam after about 100-150 rounds when you start to lose accuracy