M2 standoffs that are made of nylon which have one side that is 6mm male and the other as a 5mm deep female, they come in a bag with 25 pieces.
Ideally you can stack them to create modular heights that you need scale from multiples of 6mm and under the related products you can purchase hex nuts made from nylon and 6mm nylon screw that will provide a flush surface. Perfect for prototyping boards where you would want to isolate from electrical shortage!