Best Way to Convert battery-powered gadget to 110 V AC current?

It's what I use. $10.

For what it will cost to convert that paint shaker or buy NIMH batteries for it you could just buy a Badger paint mixer and have a much better tool for mixing paint.

My daughter gave me a nail polisher which used two AA batteries. I found an AC to DC adapter in a thrift shop for a buck. Just had to match up the voltage and made sure the amps were low. Wired the polisher directly to the adapter. Works great.

Jim

Why not purchase rechargeable batteries and a charger? Then you'll have the ability to charge batteries for all of your battery powered accessories/tools once you replace the batteries.

I prefer my paint mixer...it works great! Takes just seconds to mix.

One tool that multi-tasks!

You can buy various ac adapters at Radio Shack.  You will have to improvise on the wiring or add a jack internally.  You will need a 6 volt DC battery eliminator, I don't know what the amperage should but get one that has at least .5 amp if not more.