Solved by Nikronic in post #4 
              
              
                I think it can help: 
class CustomResNet(nn.Module):
    def __init__(self, model):
        super(CustomResNet, self).__init__()
        self.model = model
        self.part = nn.Sequential(
            model.conv1,
            model.bn1,
            model.relu,
            model.maxpool,
          …