I Can Think Of A Much Cheaper Way To Warm A Bench.

https://us.cnn.com/2022/11/21/football/usmnt-wales-timothy-weah-gareth-bale-world-cup-2022-spt-intl/index.html

Run an Electrical Current through a Resistor.

You can have one that moves in a straight line.

Or one that constantly spins, up and down, this way and that.

https://www.youtube.com/watch?v=L_AYoLZGoHo (Highway To Hell, AC/DC, Audio, Mastering Revolution).