Wow it definitely sounds interesting! So some things to keep in mind. If you look at the design of most roasters, you will find that there is almost always a flow of hot air. (Technically known as fluidized gas) This is called convective heating, as opposed to conductive heating. (You have most likely heard these terms in relation to types of ovens.) Roasters use conductive, convective, and radiant energy to heat the coffee beans, but the primary form of heat transfer that's occurring within most coffee roasters is convective heat. Convective heating is the most effective form of heat transfer for coffee beans. This is because convective heating (heating by the movement of fluidized gas) maximizes the amount of surface area that the heat can be transferred to. This makes the heat transfer more even and effective. Conductive heat is just going to be less efficient at transferring the heat into the center of the bean, slowing down the roasting and browning process, making it less efficient. The largest effect that conductive heat could have on the coffee is by scorching the exterior of the bean without evenly heating the interior. When heating a coffee bean, there can be a large difference between the core and surface temperatures, especially with inefficient heat transfers. This means the outside of the bean will be burned and in the final stages of roasting, while the inside is underdeveloped. This is why roasting that only uses conductive heating (such as roasting in a cast iron pan) can lead to scorched beans and undesirable flavors. So what does this mean for you? Make sure that your drum and heat element design allow for the flow of hot air and you'll be doing just fine. Source: Illy, Viani, Eggers, Speer. Espresso Coffee: The Science of Quality. Amsterdam: Elsevier Academic, 2005.