I have had 3 tub basses (one was plastic) and this third one is the simplest design and best. I use a dowel to attach the string under the bass and keep it from popping through the hole. I have another dowel to hold the string in place near the hole we put in the mop handle. The mop handle has a notch cut on the bottom to let it rest more easily on the rim of the bass. I do "let the sound out" with a notched piece of wood that fits the bottom rim of the bass. It's getting hard to find tubs that aren't too thin in the middle to use.

I use cotton string-never get sore fingers even at an all-weekend jam fest. I have also tried something like a weed-wacker string on someone else's bass, but it didn't behave like I expected. What I like best is old curtain sashes, but they are brittle, since they were used in this house circa 1969. But they get the cleanest pitches. My first bass had nylon parachute chord- too stretchy to get clean pitches.

I have played in a couple of old-time/bluegrass singing trios and two instrumental contra-dance bands. To amplify the bass, I use a sneaker with a good dipped heel cup. Place the mic inside the sneaker with the head sticking up out of the heel. Place that underneath, inside the bass on the floor. If your guitar player taps his foot on the stage, the sneaker pads the mic so it doesn't pick that up.