built in blenders?

[Bjazzman]

are there any companies that build custom length true bypass loops that can do a built in blend knob?

[Amitio]

I always wanted one of them!

[Bryan R. Tyler]

All the companies that I've seen that make custom bypass strips are making simple passive boxes, so adding a blend pot would mean passive blending, which would be less than ideal because of the issues it can cause.