Mentions of self harm and fake injuries too.
I must say that I have had thoughts to harm myself yet as far as I can remember I do not recall ever using a knife to harm myself, especially not to make myself bleed.
Instead I would use pens, markers, glue, paint, and even pieces of fabric to make pretend injuries. And yes I had people actually check on me cause it looked that realistic with quick glances.
I'd use just red when it's a small scratches or non bleeding wounds or maybe actually scratch myself then.
Use a blue/purple and red combo to make a darker red with glue (best with pens) to make a deeper cut look though accuracy is harder to do but eh. Easy to get rid of with sanitizer or washing with enough soap and water as that one tends to be better to wash off so then people don't ask questions.
I must say paint is also very easy for dripping blood. You can draw with it on yourself or drip it on yourself. Or drip on paper as you hold some in your hand if that's a want.
Then fabric. Fabric would be like wrapping. I used ribbon as using actually wraps and bandages would be harder to explain and a ribbon or scarf I could do anywhere and not be questioned too much as I could say it looked cool.
Other things I did but for the feeling of pain is gently push like a pen into skin, not enough to do damage but enough to make it maybe dent at the most. I'd use other things too just a pen was a common as it was easy and if you did it right no one would question it. Other than the fact you are drawing on yourself.
I had a very dull pair of scissors too that like you couldn't even try hurting yourself with. Like people had tried and failed, only to maybe indent themselves that's it. It was like a pair of scissors you can buy and it had a rounded top so you couldn't even really stab anything without opening them and it still was really dull. It cut like really well though! Like I will say that. They were metal btw. But I did have a plastic pair too at one point.
Uh anyways hm... I think that's enough things for now.
... dunno if any of this is helpful at all to anyone. But it's here incase it is.