I built mine with a plexiglass shell so I could see what is happening inside. The Hopper is not pretty, but it works. I've since replaced it with metal and added a hook and eye latch to keep the mill on when not in use.
Double sided tape keeps the plexiglass on strong. And on the other side with the tightening screws I just drilled a hole in the plexiglass and tighten the set screws to hold it on. Works great.
Built mine from some leftover wood from a cabinet project and an old washing machine motor. Used a door hinge to make the tensioning bracket. Works great, but will bind if I put the grain in before starting the motor. It's huge looking but only 1/4HP.