You buy dog gates that serve the purpose, not to show off your money-right? I was baffled when my neighbor wanted gates for his pets made of solid oak wood!
Your kennels should be offered enough freedom inside their enclosure; in addition, the doors should be easy to open in case of emergencies. Normally, people train their dogs to open the gates on their won.
Another important aspect that is overlooked when crafting or buying dog gates is the safety of babies. I have seen ads of baby proof dog gates and realized the wisdom of the advertisement.
I would not buy dog cages made of any metal. Dog cages should be made of wood only for better maintenance. You can paint a lovely and happy puppy only on a wooden gate.
It is wiser to order dog cages that can house a 4 ft tall dog.