TF2 Idling - how to automatize it?

Go back in time by about 4 years

u can no longer idle in tf2 with the command prompt, u have to actually start the game
pro tip: its not worth idling in tf2 anymore (unless youre happy with 5 weapons for idling 24 hours)

"I remember there were some methond, but when I search the internet nothing pops up."

Do you mean this...?

Be creative. To be honest, idling's kinda looked down upon, especially since Valve's done so much to try to make it obsolete (having to confirm each drop, etc). If you really want info you'll have to find a different crowd to consult with.

OP, you're a bit late to the party... Idling has stopped being a thing a while ago.

make a script to spam Enter every minute?

Idling is now useless in TF2, this no longer works after a 2013 patch.

I think valve already changed the way gift is gifted for idling people. if i'm not mistaken you can see it on pcgamer

You can't without using some 3rd-party software. On one hand it's nothing big (like some simple press enter every 30 second scripts), on the other hand Valve might punish you (but then, AFAIK they didn't punish anyone yet).