Steel tongue drum, AKA tank drum, AKA hank drum.

A round steel slit/tongue drum in the Idiophone family originally fashioned from a propane cylinder. 

A steel tongue drum can be made from an empty (often 20lb) propane tank. The tank is flipped over, the base cut/knocked off; and seven to ten tongues are cut radially into the bottom of the tank, forming the top of the instrument. Steel tongue drum can also be made from new unused tank heads. The tongues can be tuned by the maker by varying the length of the cuts, or by adding weights, often neodymium magnets to the tongues. The steel tongue drum is often tuned to pentatonic scales but can be tuned to the diatonic scale, the chromatic scale, or any set of notes the maker chooses. The instrument is played with the fingers or with mallets. It boasts a pleasant, bell-like tone. 

See Wikipedia article here: https://en.wikipedia.org/wiki/Steel_tongue_drum

See another article here: https://melodyaccess.com/a-comprehensive-guide-of-steel-tongue-drum/