Making your own will require a bit of work. It helps if you are handy with tools and enjoy DIY crafts.
Like almost any new project, the first time you make your own will take much longer than if you were making your own compressor reed valves all the time.
It is necessary to disassemble the compressor pump to find the valve plate or reed valve on a specific model of compressor.
There are many shapes and sizes of reed valves and compressor valve plates, so don't be concerned if one appears different than the one shown in the image. The question is, is the valve plate or compressor reed valve broken?
You can see that one of the fingers in this reed valve has broken off. This is not an unusual occurence due to the high heat inside the compressor pump, and the thousands and thousands of cycles the reed valves go through.
That it is broken ensures that the compressor it was removed from would not be able to build pressure satisfactorily. The compressor might just run and run, and never build pressure past a certain pressure point, or build pressure at all.
Now it's time to make your own compressor valve plate, this necessary as your compressor has no spare parts available anywhere.
Another approach is to purchase high carbon spring steel shim stock. Get a supply that is as thick as the original valve plate. If you do a Google search using the phrase - high carbon steel shim stock - you will find a number of sources.
Regardless of your choice in reed valve raw material, just make sure that the material you select is one that remains flexible over thousands and thousands of cycles and is heat resistant. Otherwise, you'll be tearing your compressor pump down again and building a new valve plate for it sooner rather than later.
Using the old valve plate as a template, mark the new material with the correct shape.
Use a scroll-type hacksaw to cut out the valve plate shape from the new stock.
To reduce vibration when cutting the thin spring steel, consider placing the shim stock on a thin sheet of wood first. This provides a base for the metal while you are cutting it, reducing vibration and noise as you cut the spring steel.
Drill comparable sized holes in the new valve plate corresponding to those in the original plate.
De-burr the new valve plate completely to ensure that it's flat and no small spurs of metal prevent a tight fit over the ports in the valve pump.
Install the new reed valve plate into the compressor pump. But first... consider the gaskets!
Odds are pretty good that in the disassembly of the pump a gasket may have been damaged.
If you don't use new gaskets when you reassemble the pump, it is quite likely that the compressor pump assembly will leak while in operation, and your air compressor will still not build pressure correctly.
Replace all compressor pump gaskets.
Since a valve plate was not easily available, forcing the custom manufacture of the valve plae, likely the gaskets for that same pump may not be available either.
If a gasket kit for your compressor cannot be found, here's how to make your own compressor gaskets.
Reassemble the pump with new gaskets and your custom built reed valve plate, and your compressor and you are back in business.