Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4883970.
Here is a set of Spacers and washers for your skateboards or roller blades. They use the standard sizes used in most skateboards and roller skates. Since the purpose of these components is to keep the bearing from touching the lock nuts and trucks they pose no problems being made of plastic, in addition to that, the spacers will only receive compression in the z axis which they were printed on, this also reduces any risks.
Print at 100% infill or use a wall line count of 4 (also known as shells).
I printed mine using PLA and they work great, so far I have been using them from about a month with many continuous hours of use at the skatepark, everything is holding up.
If you have better materials such as nylon or HIPPS or even PP you should go for those to ensure a longer lifetime of the components.
Dimensions are as follows: Washers have an inner diameter of 8mm (snug fit) with an outer diameter of 11.300mm (just perfect to only touch rotating component of bearing), and a height of 1mm. The spacers have an inner diameter of 8mm (snug fit) and an outer diameter of 11.3mm (similar to the dimensions previously stated) and a height of 10 mm.
Have fun, wear protection, and if you need taller or shorter components I suggest you use the scale tool, uncheck uniform scaling, then just add the z height that you want the components to come out at.