Sealing up the arm holes or using mounted gloves will cause more of a pressure disturbance when you move making the air less still. The still air box is not about keeping contams out of the box, its about keeping contams out of your work. Having the gloves mounted will also make it difficult to bring your tools in and out of the box to flame sterlize, something that needs to be done each time you inoculate a petri dish or do any kind of agar transfer.
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No need to use lysol in a sab, just a paper towel with some 70% iso on it is fine. This should be done to the work area every time its used no matter the setup. If you don't flame sterilize every time your tool comes in contact mycelium then you are contaminating your dishes with the myc of your previous dishes as well, something that is not ideal when trying to isolate or innoculate, especially if you are working with multiple different types of mushroom at the same time.
I'm not sure if I'm misreading your tone, but it feels a bit condescending. While you obviously know what you're talking about, this isn't my first rodeo either.
I don't bring tools in and out of my work area -- I've always put whatever I'm going to work with into the box, blast it with lysol, let it settle for 10+ minutes, then proceed with lighting an alcohol lamp in a SAB. My current project list is an upgrade from how I used to do it with a cardboard box and saran wrap.
Lysol itself isn't flammable, it's the aerosol vapors that are combustible. Gloves are an extra insurance that the SAB is completely sealed from outside air, allowing for more rapid movements within the box. Simple as that. A clear rubbermaid tote with a lid, couple holes with gloves sealed over those holes, and you've got about as still air as you're going to get.
It's fine to push people to spending $400+ on building a flow hood or buying one premade for $1k+, or they can go cheap and do a SAB or something like
@Aqua Man which will suffice just fine. Hell, I've knocked up hundreds of jars just fine in open air. Flow hoods are valuable when doing agar work or g2g transfers simply for ease of movement. Anything less than "open" air transfers carry minimal risk of contamination unless the room that the work is being performed has a high spore count, in which case, you probably shouldn't be in that area either.
Further, if one wants to go full lab style, a clean room with an isolated decontam area is needed as well as a bio suit with a SCBA is a requirement. Just saying. Clandestine mycology is not rocket science.