I was messaged firewood 9 so that's on the top of my list to try.
Seconding the firewood 9, the airpath is entirely visible, cleanable and contains only ceramic, stainless steel and wood (at the air intake). There is a silicone o ring in the neck of the oven outlet used to hold the stem in place but is not in the airpath.
(that area can get hot though). Easily my most used device, especially when taking a walk through the neighbourhood. Bought mine around $300, but looks like the price has dropped to $265.
Tinymight 2 is similar where the air enters through stainless steel baseplate, goes through the heater, then a glass or zirconia ceramic bit before exiting the glass or titanium stem. Only silicone should be a ring near the top of the body to hold the stem in place, or on an optional cooling insert. Runs about $350
Other options:
- Bakx by lamart: limited drops and requires a 510 mod, but the airpath is a glass tube heated by a coil that’s entirely outside the airpath. Probably the purest battery powered option, but spendy and often difficult to get. If you get lucky with a drop it’ll run you about $500 for a 510 mod and bakx, and gets to about $800+ with resellers.
- Dynavap/Dani Fusion/Anvil: all of these devices are metal or glass tubes with a metal oven (stainless steel, titanium or copper surrounded by titanium) on one end that you heat with a torch or induction heater until it clicks. All use silicone o rings to hold the pieces together, but the metal generally overlaps in a way where the silicone is minimally exposed to the airpath and should never be in the airpath. These heat up and cool down relatively quickly and the stainless steel dynavaps will only run you about $70-100. Dani, anvil and titanium dynavaps will set you back $200 or so.
- Tempest/Thermal accumulator: basically the same as the previous ones, but these use generally ceramic balls (think zirconia by default?) in a titanium enclosure to store more heat. These stay hot for 2-5 minutes after heating if burns are a concern and have a learning curve due to the higher heat. I believe these run about $200?