How wide to make channels in nut compared to strings?

Hi, 3d printing a nut guy again. Finally have all the materials and I think enough skill to model this thing on my own.

Exactly what tolerances should I have in the channels of the nut for the strings? Like, for example my low B string is a .59. How large should I make that channel? 1.50mm? A little more room perhaps?

Thanks for any responses!