So I came up with a slight modification of the Machine smoking device that's working really well for me. It basically turns a Machine into a low-budget Glass VaporGenie, according to my understanding of that device's mechanics. Apologies if this has been suggested before, but I searched around and couldn't find anything.
Step 1: Make yourself a standard Machine according to the instructions available on the wiki
Step 2: Remove the bit of steel scrubber from the loading end of the device, but keep it, we'll be using it later
Step 3: Take two brass mesh screens stacked together, with one rotated 45 degrees relative to the other so each hole in the top screen is crisscrossed by the wires of the bottom screen, effectively quartering the size of the holes (the decision to use two was totally arbitrary but seems to be working quite well)
Step 4: Push the screens into the loading end of the Machine as far as it seems safe to do so without risking them falling in. There seems to be a sort of sweet spot in my machine where the edges of the screens just barely reach the bottom of the threading for the bottle's cap (NOT the ridge below the threads), and they sort of catch there without wanting to move one way or the other.
Step 5: Load some crystals into the screen bowl you've just constructed. One of the benefits of this design is that you can load quite a bit of spice in there without having to repack it or worrying about melted spice trickling too deep into the bottle to vaporize!
Step 6: Re-insert the ball of steel mesh into the tip of the bottle just enough so it's good and snug, but not touching the spice or pushing the screens any farther in.
And that's it! You now have a shiny new Macheenie! The steel scrubber, instead of absorbing the DMT as in a standard Machine, performs the same heat-diffusion and flame-protection functions as the stone thingy in the GVG, and the mesh bowl allows you to load a hefty amount of spice without leakage or overheating. Just heat up the steel scrubber ball with a torch lighter and inhale. Works way better for me than my standard Machine ever did. One thing to note, though, is that this should work best if you keep the loading end pointed upward as you take your hits, to avoid the liquified DMT running out of the mesh bowl. If you're lying down anyway this shouldn't be too hard.
Let me know how it works for y'all if you decide to try it!