xxxxRay, The Christmas trees that I am making are slumped glass and yes there are a lot of tricks to achieving the best results. As my biggest kiln is only 30cms in diameter, most bottles are way too big to fit. When I slump plates over a shape, I watch very carefully to stop the firing before the glass becomes too runny (oh it does happen very fast too, around 780degrees C) . I wish I could put up pics here, sorry. I saw a tutorial on the net, showing how they slice off the thick bottom and the narrow tops of beer bottles with a fancy saw. Then they cut a line through the centre of the cylinder and put that on it's side, in the kiln (cut side up) and watch the glass slowly melt and form a perfect rectangle. Glass is certainly fun to work with.
Today I wrapped presents, delivered biscuits to some around the hood and finally got down to my shed after lunch. I had fired up a load of Christmas trees on Sunday and hadn't found time to have a good look at the damage. As I was loading the top shelf of the kiln, I heard a tinkling sound from the bottom layer. It's too risky to shake all the pieces up by moving shelves, so I crossed my fingers and fired it anyway. After expecting to have to repair in a major way, I found only a few tiny bits had moved before they had fused, so a bit of work with a diamond bit on the dremel and nobody will know about my tinkling pieces.
It's hot here again, so will try for some ugly sleep.
Night all xxx
Goodnight Jon-d x 
