Here are a few scratch-built Tau vehicle upgrades I made: A blacksun filter, a drone controller, and a disruption pod.
The blacksun filter is made from a pulse rifle and photon grenades. I admit this looks a little funny on a tank, but I think it is clear what the item is weather on a battle suit or a tank.
The drone controller is made from a pulse rifle and a wooden cap. In retrospect, it may be a little too big, but the one that comes with the stealth suits is way too delicate for a battle suit.
The disruption pod is a bauble from a craft store. Yeh, its not really a conversion. I was going for an effect like something that would disrupt radar... this "add on" really doesn't effect the profile of the tank, but again, I was going for something that conveyed the purpose of the item.
Here are a couple of pics with the upgrades mounted on a battle suit and a devilfish.
All in all I am pleased with how these turned out. I have made magnetized hardpoints all over the tank, to accommodate a fully equipped devilfish. You can see the attachment points for my still in progress flechette dischargers just above the seeker missiles.