Sockets for the bulbs?
I'm not familiar with electrical stuff, so I don't know what a shunted socket is.
If you are just trying for a waterproof endcap, you can purchase those online. I've also seen DIY versions involving bicycle innertubes (probably only works for t12, maybe t8).
I've also seen versions where they directly soldered the wires to the bulbs, and then dipped the whole end in Plasti-Dip.
May be able to rig something out of those acrylic tubes used to shield bulbs. Those usually come with a little cap that you may be able to seal onto the fixture or something.