I have a 12 word seed and I want to generate an address without exposing it to any computers. How can I accomplish this?
While theoretically possible, the algorithms involved mean that it is practically impossible. You would need to compute the seed from your mnemonic word according to BIP 39, and then derive the keys and address from that according to BIP 32.
Generating the seed from the mnemonic alone requires executing the PBKDF2 function, which is specifically designed to take a long time for a computer to compute. The time required and the complexity of the problem mean that you've got no chance.