Line a soap mold
Line your box.
Take out your freezer paper and place the box on it. Leave enough on the edges for the paper to come all the way up when folded. Cut the paper.
Put the paper down, shiny side up. Measuring against the box, fold first one side, then the other. Make the fold crisp and sharp.
Place the paper in your box, and make an indentation on each side so you know where to fold.
Lift the paper out and fold at the creases you made.
Unfold the paper, and cut a circular section from each corner.
Take each corner, line up the folds and crease the corner into a point. Repeat for all corners.
Fit your paper back into the box.
Carefully pull up the long sides and tape them to the box. You may find it helpful to place something square in the box to help you keep the paper straight and flat.
Pull up the short sides and tape them
The box is all taped and ready to go. Save the lid for later! This lining method works for log and slab molds and becomes easier with practice.