I used 4" drain pipe, an end cap and a gutter strainer.

All purchased at Home Depot.
The reason I used 4" pipe was my hand and or bait net will fit inside.
I didn't like the idea of dumping the bait out, which is necessary with smaller tubes.

I cut the 4" drain pipe to 18" and drilled 3/8" holes for water flow.
I stopped drilling the holes about half way down to prevent forcing the bait against the bottom of the tube.

The rings used on the strainer were cut from 1" sched. 40 PVC.

The bungee and hooks were from the K.F.S. site.

Picture 1 shows how I made the padeye to attach the end cap (picture 2 & 9) to the tube.
I just used PVC primer & cement to attach the padeye.

I gooped some window screen in the gutter strainer to prevent bait from swimming out the slots.

The rings on the strainer are held on with an SS machine screw, locknut & washers. (pictures 3, 4, 5, 7, 8,) show making up the strainer which is the forend of the bait tube.

Pictures 6, 10 & 11 show the completed bait tube.

Give me a holler if you have any questions

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Thanks,
Larry D