The copper mesh provides much more surface area per unit volume than screens.

I know some people get all upset about using copper mesh, but if you buy a “Chore Boy” copper scrubber, you’re getting pure copper. There may be a very small residue of cutting oil on the mesh, but this is easily removed by heating the mesh slightly before first use.

The advantage of using copper is that there’s very little spice runoff and, because of the large surface area, the spice vaporizes almost all at once. After about 5 seconds of heating and slow inhaling, the chamber gets hot enough to vaporize all of the spice. In another 5 seconds, an entire 30mg dose is gone (and so are you). (Inhaling nearly 30mg of spice vapor in under 5 seconds can produce very intense effects, to say the least.)

If using copper doesn’t seem like a good idea to you, then stack those screens, but I don’t think you’ll get the same results.