For line generating optics you can get £1 laser line boxes from the pound shop. They disassemble easily and have a few milliwatts of red laser diode that pops out and a little bit of plastic with a bulge at the bottom for the line. Worth investing a quid just for a play. I've had a few of them and the quality of the line varies a lot; not just position of the optics etc - variations in the moulding of the beam bender/splitter I think. If your £1 shop doesnt have any you can send me a quid and I'll send you one, got several sitting here now. Jim