Mine too came with the silver 'pen/paint'.. I just wasnt sure what HE used.
I have seen other blob on some hot glue first..etc.. so I wanted to ask.
* my cubes were also already 'pre-made'...
One different approach "I" did was NOT to use the wire on the cubes itself to feed into the 'nubs'..
I tired to hide those 'cube wires' to the bottom.. and then used some thin brass wire to feed through first.
Like so:
Gave me that more uniform 'bent/rounded' look..