I bought some of the recent GW steampunk pirate dwarfs (Kharadron Overlord Arkanauts) and have decided that they would make good proxies for Demiurg. Luckily, there isn't a lot of information about Demiurg apart from a small sketch and a bit of background about them being traders who shared Ion tech with the Tau.
My plan is to have three Demiurg leading each squad of drones. I haven't decided on what drones to use yet but I have been looking at Beyond the Gates of Antares and there seems to be quite a bit that could be useful.
The three Demiurg in each squad will be a technician (with a Dr Octopus style backpack), a controller (with a control staff and pistol) and an up-armoured leader (with beefier armour and a higher powered weapon/rifle - this will be from the thunderer boxed set). As with everything, I am converting stuff and will be sourcing weapons from wherever I see fit. The heads, I am sculpting.
This is the proof of concept (a controller). Note that the arms are just tacked on to give an idea of size... they will have the weapons replaced before being fitted again properly:
I have a second one on the go and that one will also be a controller. Once I have the five controller heads done, I'll start of the technicians who will have a bit of gubbins on their heads... then the leaders who will have more robust brows and more magnificent facial bristles