like I know Merino is a black/grey fabric,
so if you want to color it, it need to be bleeched and than colored by much chemic.
At the moment I am looking for a better fabric than Merino and found Alpaca Wool.
Look for it, it got some nice features.
Mechanical strong - even more isolating - lighter - higher comfort - no allergic possible - Fire Retardent and a few more things,
but the best:
It comes in natural with maaaany colors.
50km of my place is a german Alpaca farm
Crazy but good for me.
I will call them for a visit and hope they can tell me more,
and maybe they can say me someone who does custom tailoring with that
When I´m back from the visit within the next 1-2 weeks I will update you guys.