I'm counting some Icarus Lascannons as Sabre Lascannon Platforms for my IG allies, which is a great augmentation for a CSM army. But, seeing as I keep picking them up by the cannon, I tend to leave the other half of the model on the table. So I took a few minutes and figured out an easy way to magnetize the things.
Turns out that a 28mm base fits just about perfectly on the bottom of one of these field guns. So, we'll start there...
Drill a 1/8" hole (I'm using 1/8" magnets, BTW) in the center of a 28mm base.
Glue in your magnets!
Glue the now magnet laden bases to the bottom of the gun. Do your best to center them.
Once all that glue is dry, place 2 extra magnets onto the bottom of the gun. The end magnet will be the one that gets glued to the base of the emplacement.
Place a drop of glue on the bottom of the end magnet, and only the end magnet, and then carefully put your gun into the center of the gun mount.
You can see in the photo above that the middle magnet allows you to accomplish two things: perfectly place the end magnet inside the mount and guarantee that the polarities match.
You are essentially using the gun itself to help center the magnet that goes into the mount. Also, you can see that because the 28mm base is there, once the middle magnet is removed there will only be 1-2mm of space between the installed magnets. This should give you a fairly strong magnetic bond.
Now, when I pick up the model I don't leave half of it behind!
I'm still working on gathering the parts for the 2 pairs of crewmen. I have everything I need but the arms.