i use GOL or High Life in a three straight pixel line
Only works though if you have 9 pixel space for it to rotate in though. I use WALL. It has the advantage of creating a small border around itself and uses no more than 9 pixels for its smallest assembly (nothing lost space wise), and unlike GOL particles which can be interfered with by other particles "throwing a wrench" into their operation, that border around the WALL life particles keeps that from happening. Wanna weld metal? just pour broken metal powder onto a WALL, and watch it quickly melt and flow off the wall. Below have an LN2 cooled block of DMND and it will solidify into breakable metal. Sort of like smelting iron ore at a refinery.