I have tried a few types of metal beads for heating bath media and never got useful results even with copper beads. It takes FAR too long to heat up, same goes for sand no matter what consistency and salt as well. It all takes too long and it gives very shitty control over temperature.
I prefer an air bath, I've even used an air bath to reflux THF for over 2 days straight, as well as reflux high boilers for however long needed. I would be weary of using oil for this purpose, and there is no odor (unless your plate is dirty)
Just wrap foil (one layer is fine) around the flask and hotplate to make a skirt type arrangement with a few cracks for air here and there. Peach at sciencemadness has posted some pictures of what this looks like in general. It can be done several ways, find what is best for you.
It is very useful, I use an air bath SO often now, since I finally actually gave it a shot. I was always skeptical. It is very good for when you must rapidly remove heat or cool in case of overheating, just remove foil and/or hotplate.
Edit:
I should mention, this is not the best for fine temperature control. Usually the air bath is just good for reflux, but it is possible with practice to obtain reasonable temp control. This can be done by stabilizing the temp at one setting and adjusting the size of air vents in the foil arrangement
