Please, no apps. Make this as manual a product as you can. From a prospective purchaser viewpoint, I think that, while these days it seems that we may get more and more 'automated' and wired to our 'devices' via wifi, I believe that we may see a reversal of that trend down the line, strange as that may seem to those wedded to the idea of 'remote control'. You also limit your customer base if it relies on an app (to those who have whatever device can house it) - and you bind yourself into having to maintain, improve, protect, etc. that app as well as the hardware. I think the KISS principle should apply.
I can envision a small batch nut roaster (perhaps 1 or 2 cup capacity) 'cage rotisserie' that could be slid down cylindrical sides of maybe a stainless container to a height appropriate for the particular contents (perhaps several different settings) with a heating element in the bottom and some sort of mechanism that turns the 'rotisserie' cage at a steady rate. Constant heat and turning speed is probably all that is needed if one can adjust the distance from the 'flame'. Add a timer and a way to mechanically turn the cage (a small externally mounted motor of some kind should work). The cage could have several 'liners' to ensure that both small seeds and larger nuts could be roasted without falling out. Not sure that is a good description of what I can envision but I see this as larger than a spice grinder but much smaller than a Thermomix.
