I finally made a sawbuck out of a 5"x5" post that was surplus from another project and a couple scraps of 2x10. Some of the features I thought of are:

It is low, wide and stable for use with a crosscut or chainsaw.

It is a comfortable height for a chainsaw.

The overall length of the sawbuck is just a little shorter then 2 lengths of firewood.

Use a wedge on the final center cut, or underbuck to release.

It is high enough that a crosscut saw will not hit the ground on the off side.

It is low so that crosscut sawing will be down hill on the push stroke.

It is low enough so the sawyer can put a foot on a small log if necessary to hold it solid.

It is lower so heavy logs do not have to be raised very far to place on the sawbuck.

Because it is lower it uses less materials, the main cross members are 31" long.

The 5"x5" cross pieces are light weight cedar and that along with its small size make it easy to move.

The only fasteners are a few screws that hold the 2"x10"s in place. There are no exposed bolts or other fasteners that a saw can hit.

The uprights are quite short at only 8". This makes it easier to place logs but still are plenty long to hold a 20" diameter log.