There is no formula.
Bent lamination designers.
I wanted to use the shape of my skateboard in the mold so i uploaded a svg i designed in illustrator into fusion and extruded the skateboard shape 5 inches.
A note on form design here.
To design the curvature of my bent lamination i opened up fusion 360.
Choose your design software.
Alvar aalto paimio chair 1931 32.
A few thick laminations will tend to spring more than many thin pieces.
After using an oscillating sander to clean up the inner curves and a disc sander to clean the outer curves trace your shape to another mdf board using your sanded shape and then rough cut the same shape only this time leave at least 1 16 of an inch between your cut and your pencil line.
This is a perfect example of a situation where bent lamination is a good choice.
Since bent lamination is used only for narrow parts such as drawer fronts table legs and aprons and chair parts the form can be fairly narrow.
You may need to over bend your parts to account for this.
Creating the 3d model of your mold.
When you unclamp your dried part it is going to spring back a little bit from the stresses in the bent wood.
The concept is actually pretty simple.
Pictured left you can see a closeup of one of the rockers on my maloof inspired rocker.
I used fusion 360 free to hobbyists.