Centered variable weight

Hi everyone!

I designed an alphabet for a fashion magazine and I’m now making it a font. That’s the ‘easy’ part. I’m making it variable with one axis (weight). It’s a geometric monospaced one, grid based and made by a line with a consistent thickness. I would like to give the possibility to the Art Director of the magazine to control the weight of it. What I find hard is to make the weight variation happening from the center of the line and not increase/decrease to/from the right like a regular font (see attached). Anyone who can help me out?

Much thanks! G