ORIGINAL: marc s

Just make one, the problem I find with the pliers type is they are not easy to get into spaces when you want to security wire after installing something, so grab a length of K&S steel rod, around 4-5mm in diameter and long enough to hold in your hand so a few inches extends past your grip.
File a flat at one end by filing both sides until its about 1mm or so thick, drill a hole in the end suitably large to accept two pieces of your chosen security wire.
To use (once wrapped round tube) take one end of wire and pass through hole, then take the other end and pass through hole in opposite direction, pull wires until head of tool is an inch or so away from tube to be secured and rotate rod in one direction, the wire will twist into a progressively tighter grip. Once done snip off and remove two ends from tool - done.
Never fails and so simple to use.

marcs