@ Old Lady---you can search Pinterest the same as we search these forums. In Pinterest, put in your key words (big search bar, top left). I just entered "marble slip clay" and got a bunch of images, several like the one initially posted to begin this thread.
I'm with oldlady on Pinterest: I often search *Google images* and it invariably ends up at Pinterest. Once you get to Pinterest and try and follow any links from there you end up going around in circles.
I usually start an image search now with "-Pinterest" in the search term.
I make all my own bats, I also had to drill my wheelhead to fit bat pins: I first made a template with a 3mm hole at the centre to allow me to centre it on the wheelhead in which I'd also made a 3mm hole at the centre, a 3mm diameter masonry nail serves as a locating pin.
I made the holes for the bat pins asymmetrical: one of them is about 90mm from the centre and the other is about 120mm - my bats can never be put on the wrong way cos it would be very noticeable.
I've obviously kept the template so that any future bats can be drilled out to the same dimensions, a 3mm hole at the centre and a couple of clamps and it's ready to go.