Our only real rule was you couldn't "hide" a heavy weapon on a regular trooper -- they were too obvious to see -- but otherwise, we just talked about what each vehicle, squad, etc. had as weapons.
Well, the new normal is WYSIWYG. Which is fine, but models are REALLY expensive!
So, I have embraced the new trend -- MAGNETS!
Last weekend, I went down to my FLGS and bought a Land Raider Redeemer/Crusader. The kit is designed to build ONE of these two options, but if you are clever; you can build two!
Here are some pics
Land Raider Redeemer It has Hurricane Bolters in the sponsons.
Land Raider Crusader. It has Flamestorm Cannons in the sponsons.
Here are all the magnetized bits.
I think you can see, on the sponsons, that I have magnets set up in a diagonal pattern. These match a diagonal pattern in the hatchways. I place them this way so I'd have a better time drilling. The corners are clearly marked.
For some smaller parts, I just glued a tiny bit of steel onto the part. The magnet holds the smaller parts just fine. The larger, heavier parts have paired magnets.
GW only includes two (2) pieces to attach the guns to. These pieces rotate within the sponsons. To be able to mount both pairs of weapons, you'd need two more. Some folks magnetize these pieces and then attach the guns with magnets.
I decided to build four (4) magnetic rods, magnets at the top and bottom, for gun mounting. I used plastistruct tubing 3/8 inch diameter. I put a bit of sprue inside the tube and then I pushed it down with a disk magnet. Using the magnet assured that there would be JUST THE RIGHT AMOUNT of space for the magnet in each end. See sketch:
Then I glued the magnet on top of the sprue bit INSIDE the rod. The weapons were then glued to each of the rods.
I also embedded eight (8) magnets on the top of the Land Raider. This will allow me to mix and match bits on the top like the antenna, storm bolter, hunter/killer missile, spotlight, etc.
Anyway, I'm not an expert painter, but I think it looks pretty good.