The example here is the outside of a mold but it can work inside too.
How to sew plastic sheeting.
Lay the sheets over the mold and up the retaining walls.
Fold it into the size that you want and then add a piece of velcro to each end with your sewing machine.
Measure the inside of your oven.
If the plastic sheeting is very thick you can use staples about 6 inches apart.
Place the paper clips at approximate 8 inch intervals.
How to sew on pvc fabric or imitated leather using either a teflon foot or scotch document tape on your normal pressure foot.
Then open up that top flap again and sew all along the sides and top.
Pin the plastic sheeting together using standard sewing pins at 3 to 5 inch intervals.
I ve sewn on a lot of pvc.
So that when you secure it shut the velcro pieces match up.
Remove the excess water by squeezing the sheets over the bowl.
Lapped seam for extra strong seams and to ensure that the seams donot have pressure because of the seam stitches the.
Lay a strip of tissue paper the same length as your sheeting on your work surface or the floor.
Press the sheets into the mold so that they form to the shape.
As you ll need to put the plastic sheet into the oven this is your size limitation.
Using glue at the seams in addition to the stitches will.
Use heavy duty topstitching thread for top stitching and sew with a longer stitch length than normal 4 is good.
Dip the sheets in bowl filled with room temperature water for 1 second.
How to sew plastic sheeting.
Make adjustments appropriate to the specifications of your project.
The sheets should be wet not dripping with water.
Have a mold ready to use.
Secure the layers with the large coated paper clips.