I did this to myself following the guide from botox official website. Got better results than when trained and licensed nurse did it. I would not do that to others for liability and just common sense reasons. They could follow my example, but on their own.
I'm using the green
owen mufford pen. It's very convenient for injections with a single hand. You dial the number of units in advance and just need to press the trigger for injection, no need to keep pushing like with humapen and clones.
Standard dilution is 2.5ml of sodium chloride 0.9% for 100iu vial of toxin. Then 0.1ml (10 U100 syringe units) is 4 IU of toxin.
I did filter China-sourced toxin with 0.22um nylon 4mm syringe filter for extra safety, toxin worked just like it should.
If you use sterile water or BAC water instead of sodium chloride, it stings for about 10 seconds after injection. Unpleasant, but tolerable.
My friends liked my results so much they ordered kits for themselves.
Edit: added links to pen and Botox guides