It depends on how serious you want to get...Just make one,that works,or one that works really well.Inner tube bands will work,but not as well as some tubes and flat bands,such as Theraband Gold..To get the most out of them,you need to establish your particular form and draw length and cut the bands to length accordingly..Band widths determine draw weight and ammo size used..It can be a bit overwhelming at first,but can be fun learning it as well..{OTT},over the Top or{TTF} Through the forks is mostly personal preference,but some styles of frames,dictate one style or the other,such as a PFS or Pickle fork shooter,which is a small frame with little to no gap to shoot through,so you have to shoot over the top,in a flip style..Its a lot of fun and be carefull or you might get a bit obsessed...A lot of similarities in Cats and archery...