It's simple. Maybe your washers are too small and slide right trough.
Or you just want to use them as space holders, so you don't overthighten the bolt and crack the plastick.
Again, it's simple. just follow these simple instructions :
Load your washer into your slicer.
Select your object and ajust the height using the scale tool.
Slice and print your object.
I hope this helped you, to ajust the height of your washer.
Let's say, it depends.
If you need it to withstand temperatures of over 150C°, use Nylon.
If it has to protect the material under it, use TPU.
If it isn't under any stress at all, use PLA or PETG.
The author marked this model as their own original creation.