You can play kalimba-like instruments with mallets, but it helps if the keys are large. Pictured here are a couple of mallet kalimbas with keys a half inch wide. On one of them the keys are up to 9½” long, the other up to 6½”. Playing with mallets, especially hard ones, tends to favor the overtones more than the fundamental, and in the longer-keyed instrument shown here the fundamental isn’t audible. The tone is a clangy-sounding mix of overtones. In the instrument with shorter keys, the fundamental is audible if you play with very soft mallets such as superball mallets. This one makes a very nice bass, as the mallets impart a punchy sound that is different from either plucked tines or plucked strings.
In the audio clip the smaller Mallet K (the one that works well for bass) is joined by a classical guitar, Y-String Guitar, and miscellaneous percussion.