The simulator itself is fairly simple. At its core, it's just a constant-current source. Make sure that it's safe: isolated from the mains, delivers the right amount of current, and ideally has some cut-offs in case the electrodes come loose (you don't want it to keep upping the voltage if there's a marginal connection).
The bigger question is what you want to use it for. I think we've got a ways to go before we have "fire-and-forget" procedure work for everybody. Depending on where/how/when you stimulate, it's sometimes possible to produce the exact opposite of your intended effect. One of the headsets marketed for improving gaming had a big dust-up over that.
I was considering using it a few times a week to see if there was any lasting improvement in focus. I've used one before years ago that a friend let me try for a few sessions and my subjective experience was that it had some fairly long lasting positive effects, could've been placebo but I figure it's worth giving it another shot.
Thanks for the info, it looks like this device does have an auto-off feature for when the electrodes aren't in good contact and it is battery powered so no mains connection. Also has a ramp up and ramp down for current at the beginning and end.
The bigger question is what you want to use it for. I think we've got a ways to go before we have "fire-and-forget" procedure work for everybody. Depending on where/how/when you stimulate, it's sometimes possible to produce the exact opposite of your intended effect. One of the headsets marketed for improving gaming had a big dust-up over that.