Used painless circuit boss harnesses
 

I have a couple of used painless harnesses.
One has longer wires, one has short. I figure between the 2 it makes it easy to swap pins around and configure as needed.
These are actually made by Packard, so the fuse holder pins are available new also. Hella and others make the relay pins.
The fuse holders can be attached to each other so you can stack them up.

$30 shipped in the lower 48, $20 local