[Jeffy]

Many teams have used PVC pipes with T connectors on the ends for their arms. Inside the T connectors you will need an endcap each end that will connect the smaller diameter axle to the pipe, or a bushing to the pipe.

These can be made on a lathe, but I'm guessing you don't have one. This is the first year we have one.
Here is how we have done it in the past-
1. Buy a hole saw that's interior cutout is the size you need, or slightly larger than needed. A bit larger is likely what you will find.
2. Cut out as many of endcaps as you need from 3/4" red oak. Do not use plywood or MDF it will split.
3. Carefully line everything up and anchor each piece and enlarge the hole to the size disired.
4. Use a bolt and nut to compress the endcap
5. Put the bolt in a drill press (or properly anchored hand drill) and use a file until it is the size you would like.

Hole saws can be found at nearly every hardware store.