Similar to the ones I used for my amigurumis, only bigger and they don't come with washer.
Washer is the plastic you put behind the safety eye.
Safety eyes with washers
I googled "install safety eyes without washer" and the solution is to use glue.
So I decided to try my own way. Making the washer using bottle cap.
All you need is bottle cap, nail and hammer.
Make the hole at the bottle cap, it doesn't have to be neat, just make sure it's not to wide or to tight for the safety eyes.
You can cut the side of the bottle cap, but it's not necessary.