I normally use milliput
but I read somewhere that did it with a soldering iron and the back of an exacto knife
wich means you get a heavy duty exacto knife you take a small series blade and put it in their around backwards
you attach a copper wire 2 the blade and to the soldering iron
and then you start 2 make the zim
be carefull tough test it on very old model
if you dont like dont use
but I liked and I got some nice results
but I also love my milliput or the zim sets that you can get from verlinden or other after market products