I use cardboard for fixturing aircraft parts and the only way to make that work is cutting multiple sheets and gluing them together over a known good form. A jig saw wouldn't be accurate enough for my purposes. The 40w cheapie is dead on so works good. Cardboard is crappie to cut, smelly and flames up a lot.

I am wondering just how valuable the auto z set will be for hobby use? After using mine for a while I find I prefer the spacer tool. The one advantage the auto z would have maybe is safety possibly. Any time I am fiddling inside the case I remember when I first got my machine and unknown to me (at first) it was intermittently firing on it's own from time to time. I am just lucky I always respected the beam path with my fingers. By the way after using this thing I am not so afraid of it and the one interlock I hooked up is now disconnected. You do have to open it from time to time and it's a bit like a propeller on an airplane (except not near as dangerous) and you just have to always respect it. Just like my large metal lathe, I keep bulk quantities of chop sticks at the machine and any time I open the lid the first thing I do is grab one and that's what I move things around with if the power is on to the machine. Helps me to remember what I am doing. During alignment I always have a paper precede any reaching in to the beam area or I stuff a piece of aluminum up in the corner to block the beam entrance although I usually just turn the power off to make any adjustments. I am used to stopping at critical points, taking a breath and thinking before doing something I know could hurt me. Just like pausing at the end of the runway, looking for traffic,scanning controls and instruments and checking traffic again and THEN committing to going. With the CO2 I only have my regular glasses which will block the beam and I wear them all the time.

By the way if you use the K40case there is a hole in the bottom, I think the air entrance, and I have had it scorch a paper I left under it once. I fashioned a piece of sheet aluminum to be under there to catch parts and stop the beam. All aluminum should be dull in finish so it absorbs, not reflects.

The K40 25 watts is I think a lot different reflection and safety wise than say 200 watts.Still a good machine to develope good habits on.