I have decided to make a smaller machine to test out the delrin nuts I bought off ebay. They are 10x2d and round. How do people mount round delrin so it doesnt spin? Should i flatten one end.

I have bought some trapezoidal rod from merchant dice size 400,400,200. Im thinking of encasing the machine in mdf and trying out a moving table design. The size should fit on my desk and the casing should stop some of the dust and noise(my main problem with my original router).

Ill only be able to make items less than 300x300 but will be good for testing. thanks for the advice.