Great ideas.. great design.
I hesitate in saying anything negative because it can come across a bit, well, negative. I'd also add that I am no expert in these matters.
But my two pennies worth would be that from a commercial aspect, even though what you propose is both stylish and functional, you would possibly have a high production cost. All the little intricate bits would need machining. every little extra detail, protusion, recess etc. would cost.
My view would be that this problem has (almost certainly) already been solved and you would be better trying to use a solution that is already in production. Buy in large quantities where possible to keep the price down
I may be wrong on this of course.. as I say, I'm no expert.. far from it.. I'm just really interested in design.
I think a good start point is getting the main tank design. I have some ideas but I'm no draughtsman..
Most "off the peg" solutions I've seen revolve around a series of glass/acrylic pods, heated by a heat mat. But, I think that, given the increased climate management you get with a moat/water-based offering, it is still worth investigating.
I think that the nest units in the tank would need to be "sealed" so that ants couldn't dump in the moat. Feeding station could be external. If the units were sealed then you might not need a moat round the top.
But if it was all sealed then how would you get access to drop in the ants in the first place and to prepare the nest units??
A lot of questions... not many answers I'm afraid. That's where you come in

Design like the wind Roddy
