I won't post the pictures here, will keep them to the correct section. About 8 pictures of it (not so great quality but you can see what I did with the Y-Tong/basin etc.).
http://www.antstore.net/viewtopic.php?t=5676
I'll post any pics in the future on that other thread, not here, as this was meant to just be a discussion on using Dremel for Y-Tong!
Oh, but just to keep it on topic and in-case any other Dremel newbies come looking;
JimmyVE was right, the Y-Tong cuts REALLY really easily, just about anything can cut in to it - if you press your fingernail in to it, your fingernail can sink in a little too! I personally used this bit for everything;
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Which is bit # 134, labelled as "High Speed Cutter". Did it very effectively and what felt to me to be a good size first time for the tunnels etc.
Be sure to do it outside - the Y-Tong will basically disintegrate to dust when working with it, my outside path is now covered in fine white cement powder, looks like the sand-man died out there
When finished give it a good wash off to wash all the powder away, this will let you see if the tunnels are carved properly etc. too, but you don't want your ants wading around in a load of very fine white cement powder.