Strato, pretty much said it all.
There has been rumors of Mato doing an all metal Sherman, but that's all it is rumors.
The Tamiya lower is your best bet if you want metal, its a bent aluminum hull.
HL Panzer III | HL Tiger | HL Jagdpanther | HL Panther | Mato Sherman
Hooben Elefant | HL Pershing | HL Bergepanzer IV | Tamiya Leopard 1A | WSN T-34
HL "Golden" Pan-Tiger | M16 Halftrack | HL Panzer IV | Tamiya KV-1 | Tamiya Tiger