"Giant (Metal) Monster Theater" from Metal Men vol.1 #33 (DC, 1968) by Bob Kanigher, Mike Sekowsky and George Roussos
The Metal Men are one of those crazy concepts straddling the line between superheroics and humor comics, a bit like Plastic Man (the similarities are obvious), that you'd have to work hard not to make fun. Some have, obviously, but most Metal Men stories I've read have had no problem with that. The original series is definitely a collection I need to finish some day. King Rex Kidd's Comic Kingdom certainly provides incentive.