I had been cementing bricks quite often, putting all the pieces together. The stuff on this page happened over about three days.
The first step was to attach the M-Board to the slab. I had previously cut the board round the same way as for the floor. I used a very liberal amount of the cement, I had plenty left. I did this at the same time as cementing two halves of the ceiling together. I should have waited as it wouldn't have required clamping then. I could have put the 100lb slab on top of the board, it would have clamped itself. Oh well.
The next day I took to shaping the slab round. This was actually quite easy. I had the round M-Board attached to it, so it was only a matter of sawing/grinding/sanding the extra off. I used a hand held wood saw to saw off the large chunks, and then to grind bits off. The picture here shows the result of doing this. It was actually quite easy. Sanding by hand then resulted in quite a nice circle.
Lastly some more riveting, and I have my lid ... pre-hinge. I'm still not sure how that's going to work.
