I'm no expert but I would think that if you can get an overflow drain that will accommodate the thickness of the material it would be easy to add the overflow/drain setup to the stone. I know in the local tile shop they have a travertine carved tub but I don't know if there is an overflow or not. A plumber could probably make something for the overflow and drain, or add length to the overflow/drain fixture, or have it made. I made my own SS sink recently, but without an overflow, and set my own drain. I followed along with the Buck's County Soapstone video to draw up my plans (with a lot of stop and starting of the YouTube video). They used a Kohler sink drain that could give them the depth that is needed for the stone. But even still I needed to take material out around the drain to get the hole thin enough to accept what I think was a 3/4" thickness for the drain and nut. So that is what I used. Taking out material also allowed me to create a slope to the bottom for drainage. So slope might be something to consider. I don't know how much slope you would need for drainage - probably around 2% at the min.? I haven't done the length to figure out how much material that would remove if you did it with a flat bottom. You don't want to get it too thin at the drain end. Unless, you put the drain in the middle near the back long side then you could split the difference. BTW, My sink holds water too :)

I'm pretty sure I know what you're talking about, and I have seen this happen before. Do you have a screw smack dab in the center of the drain cover? Without seeing pictures, and without seeing behind the tub, I'm going to "guess" and say it's a Gerber waste and over flow. I'm also going to assume you have to lift a lever in order to stop up the water in the tub correct? You can either change out the trip lever for a blank cover plate, and the drain can be changed out to a "lift and turn" style drain. All of this can be done from the front of the tub. If you know the manufacture of the waste and over flow, you can contact them to see if they have different strainer style. If you have access behind the tub and it's Brass...it's most likely a Gerber. But Gerber also make a plastic waste and over flow as well. However, if it's plastic, it could be a number of manufactures. If it were me, I would replace the trip lever with a blank face plate, and install a lift and turn. Since the lift and turn's seem to gather hair much quicker, you can leave it out until you use it for tub applications, and purchase a $2.00 screen from your hardware store to collect the hair. The hack way of doing things would be....concave the strainer yourself by pushing it in. It's very easy to do. : )

i am doing a full reno. i have a 25yr old cast iron kohler villager tub. i thought after this headache of reno i could at least enjoy a new bathtub drain assembly that actually works. however the head of the tub is and exterior wall of concrete block. and i am afraid to let them take out the tub cuz i know soemthing will happen. even if i do get the tub out how do you replace the drain assy when you cant get to the head of the tub? are there any other simpler fixes for a working tub drain? preferably a kohler product that can match my new finishes (no the current drain assembly is not kohler!) please advise. as it is timely. thanks

I was thinking the obstruction was right below that cross piece in the drain because it looks kinda' white in the photo. Since that isn't the case, the screwdriver idea is no good. Do you have hard water? Problems with minerals accumulating? How long have you lived there? (Hard water deposits & long hair--previous occupant?) My laundry sink kept getting more & more sluggish. When I took the drain pieces apart, I was flat out amazed at how much hard water deposits had obstructed the pipe---close to 50% blocked. I would not have believed it if I hadn't seen it with my own eyes. And my water isn't super hard, either.