I ordered these .063"x .031" rare earth magnets from Magcraft and installed them in my Sentinel. I then added magnets in the weapon systems and their respective accessories. The magnets are small and easy to lose, so if you decide to order some be careful. In my fingers they felt especially tiny.
I have the options made ready for both Armoured and Scout Sentinel. I have another kit and I plan to build the same configuration with it. I will then use the left over Armageddon pattern bits to convert some eBay salvage jobs I won last year.
I added army markings and unit id on the walker. After the unit gets some kills, I will add the appropriate kill markers.
Once I finish with the eBay Sentinels and the other new kit, I'll have five total. I plan to convert some heavy bolters and multi-meltas to round out the weapon selection. It is always fun to herd Ork Boyz from the flanks :D