To this day, I feel like I don't have a good intuitive feel for how power dissipation turns into heating -- that is, if I waste 1 watt of power as heat into a device the size of a coffee mug, how hot does it get? How about 10 watts, 100, or 1,000?
I realize quite well that material selection, air flow, surface area, et cetra make huge differences. However, it would be nice to have some rules-of-thumb as a starting point to sanity check whether a device would be cool, warm, ridiculously hot, or an ignition hazard.
What are some of your approaches to estimate how hot your project will get without modeling or building the actual device?
Just to clarify, I am more interested in the steady-state temperature of the device (or at least the "touch surfaces") from continued operation; not the immediate heating effects of a momentarily on device.