You can order these aluminum boxes from Mouser Electronics, and other parts suppliers. The AC-1404 is priced at about $10. Some were purchased brand new at a hamfair for 50-cents each.
Here you can see the VFO before the buffer board installation.
This illustration shows the VFO with the buffer board in place, with the module awaiting the addition of mixer and tuned RF front-end circuitry.
