Make sure your acetate edges are evenly just below the score lines so that your top will be on straight.
I then laid the box on it's side and used my bone folder to rub the acetate and cardstock together until the glue held well.
Now, find the side that you want to be your front of the box. Trim about 1/8" off the front flap with paper trimmer.
Turn this side to be facing you.Fold right side flap in.
Fold back flap down.
Fold left side flap in.
Fold front flap down. Now, note which edge of the left flap corresponds with the back edge of the front flap.
Then use slip punch centered on that edge.
Now the top flap will tuck into the slit and hold the top closed!