I thought I'd play with the perspex this evening - I thought half an hour would be enough and then I could get on with something useful. Fat chance - the trouble is when you start with this game it's hard to stop. I started with plain light - then remembered the roll of gels I have stashed away so played with them. Then I got the pop out of the fridge and added that to the glass - then, then, then..... before I know it the evening has shot by and I've other stuff to get on with - hey ho............