So this is the finished product.
I had a very helpful
GW staff member help me out with the paint scheme and assembly for this hive guard. Decided to share the knowledge!
Basically you will need
Magnets and drill bits
Green stuff
Mostly standard magnetization but here it is anyway
As you can see both the arms come off - For the body I drilled a 3mm (or 1/8 inch) hole and shoved the corresponding magnet in the body. I use green stuff to make the magnet fit better.
http://imgur.com/a/DZbeE#1
Now I used a 2mm magnet (1/16 inch is almost the same) and slotted it in the impaler cannon where the left arm connects to it. You can use a 3mm (1/8inch) magnet for this but I find the 2mm magnet fits better.
http://imgur.com/a/DZbeE#2
Lastly I did misalign the impaler cannon a bit so the left arm could not reach and connect to it - add a blob of green stuff to extend it and stick a magnet there and your OK!
http://imgur.com/a/DZbeE#0
Coming soon - Magnetic Scything talons with some extended carapace stuck to it to convert it to a tyrant guard.
Some reason the encoded images dont work with imgur? bit a forum noob sorry!