And what power sould buy/can you give me an link for a better one(but to be cheap) on aliexpress?Chances are that your 405 is already over spec and will meter at more than 5mW. Instead of trying to mod it, just buy a better laser.
Why does the laser you have disappoint you? Why do you want a stronger laser? What do you want to be able to do with it?
Cheap? How much are you willing to spend?
If you are good with soldering you can put together a dangerously powerful laser fairly easily for not much money. There is tons of information here about how to do it. Look around the forum and read. read, read.
You will need protective goggles for your eyes that are made for the wavelength of your laser. Even reflected laser light can cause permanent blind spots. Buy the glasses before you buy the laser.
From where are you , sir ?I will be ready to sell you spare parts, and you can create a fairly simple circuit with ic lm317
i from Viet NamFrom where are you , sir ?