Hello everybody!

Please, help me to solve the question.

I need to make two PDMS covers - top and bottom,
like this: ___----___ and ---__---, with the same length and width (heigth does
not matter).

For this I've tried to make THB and SU8 molds, using same size opposite masks .
But after preparing PDMS I've figure out that real dimensions are totally
different (bigger for "top" and smaller for "bottom"), means that during
UV/Developing actual size of masked PR is decreasing.

I want PDMS like this: ___----___ and ----__----, but I;ve got  _--------_ and
-----_-----.

Could somebody advise me a formula, how to calculate real change of size  in
mask/UV/developing steps?

Or provide the solution of preparing equal opposite patterns?