This is a little hack to make it with 50mil ribbon cable, the ony i could buy locally.
I got 50 wires cable but you can do it with different ones.
Using Wilba s advices, cut 50mm in length
Then strip away 5 cables (this will be different if you use a cable with more or less wires)
Make a sign 5 mm away from each side and score a little bit in depth (without touching the copper) with a cutter along the line, do the same on both sides
Separate it in 3 smaller ribbon cables of 15 wires each
Bend along the cut lines on both sides and pull the 5mm of plastic 3 or 4 mm only
Put quickly some solder on the exposed copper, at this point it doesn t matter if there is some in excess
Pull off the 5mm of plastic tubes
Cut every second cable
And finally quickly move over each exposed wire to fix the tips/remove exceeding solder
(sorry no pictures!)
Simone