That depends on the size of the hose, the width of the form... I made my own hose so it might not be standard... I have about 7/8" to 1" between an empty top and bottom form... Do a dry run with lams and riser in the form... Have the forms squeeze that hose so it is just a hair of a dog-bone shape... That is perfect... I will try to post a pic of a diagram I just did about two month's ago... I had an issue with the lams wanting to slide sideways and my form shifting...