How to make 410 meters of rainbow?

Its easy :-)

Take a braid of about 100 gramms of handdyed merino top.

 Half it and spin half of it to a nice single..

 Then sipin the other half in the same color direction...

Then ply it...

Then skein it...

And voilá, there it is... some happiness at the beginning of fall...
410 meters, 2 ply.
Mernio, handdyed...by me.