ERC1155D.md

function mint() external payable {
    uint256 _currentIndex = currentIndex;
    require(_currentIndex < MAX_ID_PLUS_ONE);
    require(msg.value == PRICE, "wrong price");
    require(msg.sender == tx.origin, "only EOA");

    _owners[_currentIndex] = msg.sender;
    emit TransferSingle(msg.sender, address(0), msg.sender, _currentIndex, 1);

    unchecked {
        _currentIndex++;
    }
    currentIndex = _currentIndex;
}

gas cost to mint: 50,998 (optimizer set to 10,000)