I can't think of any way to know the herbs are used up other than the taste for you. Other than that, the Ion meets your criteria and is the only unit I have that I can think of that would be relatively safe for the blind. Once it is set up to use the only place that gets hot is the basket inside. You can leave it in there until it is cooled down later. Very few buttons and durable. Big and heavy enough to handle you bumping it with your hand as you look for it. It is the only vape I have that I think I could use relatively safely with my eyes closed.
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Vitolo -- any thoughts here? Have you ever recommended a vape for a blind person before?
Yes... many
I have worked with a few visually impaired patients, and a couple that were totally without sight.
Once I was connected with an unsighted friend on skype, and I verbally was back-seat driver as he moved for the cam (his mom was present, but stood respectfully back).
The best successes visually impaired friends have had in Portables has been with the Vapir NO2.
The timing of the preheat is easy to get down, and getting the meds down in there is a snap.... the oven is not exposed, unless one were to force their pinky's tip down in there.. and then it is only the tip.
It shuts self off, and is easy to quick clean after uses.
The big cleanup would need to be learned, but the structural discretion of features is tactile/friendly.
Nothing outside gets hot at all.
It is sturdy
It can be used plugged in.
Please... if you are a hater (NO2 hater) this is not the place to start a "rant"... this is a serious question, and I am coming forth with a heartfelt answer....
No glass involved, and it can be dropped from belt level without panic.
If you wear baggy pants it can be dropped in a pocket for a minute while you feel around for your keys and wallet.
SOLID state-
I am going to vote Silver Surfer, with Spherical setup.
NEVER hands free SSV for a blind vaporist.. because glass plugged into glass at a 90º angle makes NO sense.
the upward sweep of the SSV is good.
Original hand held is nice, but a fraction of a second of doubt/faith each time you are about to make contact.
spherical... ahhhh
allows one to proceed wand with finger slightly... find that parabola, and glide in for gentle landing and .... smooth aiming.
never gets hot at spots a finger can touch, that parabola is a safe friend for a "guy with a limitation in his eye"(
He... who cannot see)
Hope I helped.
The choices above are the result of trial and error...
I tested all vaporizers on my signature, and allowed those visually impaired patients that participated access to try and to use them all fully as though they had no assistance available.
These were not choices I made for patients but rather observations of the patients themselves.