Below are the basics of what I did.... although I had many a side trip.
I stated with a 2018 arrow that was suggested in an earlier thread by bonsaibill (thanks). Drill the back of the casing out and tap it trought to the front of the casing.
I then gaged where I wanted the internal components.
This is where the fun started. I wanted the top a mix of wood and casing but I wanted everything the same height. So I cut the casing and the wood to the same angle. But before cutting the angle in the wood I drilled holes the same diameter as the inside of the casings.
The end that connects into the lower barrel needs a hole for the tube that twists the mechanism. The top casing is solid. You can see I cut the end of the casing off and milled a small recess for the clip.
Another photo of the top assembly.
Here is the very top I drilled out the center because I thought a plug would look good.
Here are all the parts ready for assembly... or I thought. The angled casings took a long time to fit so the angle and wood height was acceptable.
This is a shot of the two halves after assembly. The tube in the top goes inside the arrow tube and over the twist mechanism in the lower half. The arrow tube in the lower half fits between the casing and the upper twist tube in the upper. Together the pen is very solid. But if the arrow fits to tightly in the upper half it make turning the pen too hard. So you have to fit the tubes and the casing holes to have a solid feel but not to tight a fit.
Any comments or suggestions are welcome.