That's what I was thinking. Since the zenith delrin top isn't affected by the heat, then why not just make a whole topper from Delrin? I've been trying to do some research on Delrin's melting point and toxicity. So far, the material limits I found far exceeds vape operating limits. I still need to do some research on what chemicals might leech out at lower temps ( 200 - 300 F ). But I was thinking that if the zenith delrin top cap can be right on top of the coil, then why not just make a whole cap out of the thing. It should be so much cheaper than stainless.
I just got around to setting up my Zenith V2, in top fed mode for now. I Don't know about an all Delrin top cap but the delrin insert on the zenith makes a big difference. Little to no heat transfer to the drip tip. Also because it protrudes through to the other side of the cap a little it takes some of the space out of the vape chamber. I think that also does something for the flavor. I'm not sure what it is the flavor is awesome.
So I setup my usual dual coil 12 wrap Nichrome 80, 1/16th ID @ .4Ω. The chamber is wide and ends up being filled about 1/3 or more with cotton for top fed dripping. The coil can pop blister splatter all day long and with this design the juice splatter never makes it through the drip tip to your tongue.
So, if I were to suggest improvements for bottom feeding it would be to make the holes in the post lower, shorten them and bring down the cap height a little. Keep the Delrin insert. Keep the screw-lock AFC ring with the slotted air holes.
The short wide vape chamber puts out impressive vapor and flavor just like the Rip dude said. And you can go as hot as you want with your coils without the blistering tongue splatter.
Not really sure yet how I'm going to make this thing bottom fed. But so far I like it better than anything else I've tried to date.