Sure, Kermit
I'd be glad to take a stab at that, let's start out with substantial having experimented with a few chunks in my time, I've found they need to have the following basic design. Make sure that it is heavy. To not move around as the rifle recoils as this just simply does terrible things to your group also I have found that they should probably be somewhere between 10 and 14 inches wide. I have seen some wider than has and don't believe that it really hurts anything other than on a tight range. I personally think it takes up unnecessary space. Front to back. Things should probably be at least a 10 to 12 inches long. At the base. Once again, so it doesn't rock back and forth during recoil. I would suggest making an out of a rather heavy hardwood oak is always my first choice.
Adjustable some prefer to have for lack of a better word, a tower with a slot in each one a block of wood with a long bolt run through it so it can be raised and lowered, and also the legs can be at different heights, allowing for unlevel ground. I have seen others which have a block of wood or a box with an array of boards to stack on them, varying from about 1 inch to 1/4 inch thick. Most of these have either pins that come up through the board. You stack on or bolts that go down to where you can tighten them in place Once again, if you go this route, be sure not to get it too top heavy. Unless you have a wide enough base to hold it stable.
One of the things I'm starting to see people want to when they built their chunk is to find a way to trap the rifle in the chunk, much like a bench guns shooter would do on his bench. In the circles I travel in. This is not considered to be good. Your rifle barrel or your sandbags should you use one or your kant block should be able to move freely on top of the chunk. I have seen some individuals who simply bring a block of wood and a sandbag and do very well. It does seem that your imagination and a few simple rules are your only limitation. Oh, never under estimate the value of penning one to the ground with some rather large spikes.
As I am giving my son the chunk that I have been currently using will and building another one. When I get the new one built. I might post a picture or two of the I just hope it doesn't take a fork truck to move it around. Well, now that I have probably completely confused you all quit for now, try to get some pictures and post them. Stay safe.