Well I made and have seen many checkering cradles. They look great, but how do you anchor them to what so they are sturdy and not moving when you use them. Like I said cradle looks good sitting on bench but useless as I can hold the stock with my one hand and checker with the other better. Even prop the stock between my arms or legs. Some one give me a clue on how you mounted a cradle

Can't say I have much experience checkering other than chasing the lines to crisp them up after a refinish job.
But the most useful way to mount anything in a vise for maximum move ability, that I have done, is to mount it on a bowling ball rig.
You can look it up on YouTube and get a better explanation of how to make one for yourself.
But it involves a couple steel rings cut with the proper circumference for one to support the ball while the other clamps down on it with bolts to adjust it's movement.
Great for working on shaping small parts and awkward items too.

You clamp it in a vise. That way you can move it up and down, and the cradle allows 360 degree swivel.

I worked standing.
My checkering cradle had a hole in the middle of the base. Work bench had a hole drilled in it too.
Had a large carriage bolt coming up from the bench and a big wing nut to lock the cradle in the position I wanted.
There are other more sophisticated methods but that worked for me.

When I started checkering a dozen years or so ago I built a nice cradle using Unistrut and a Wilton Pow’r Arm. Worked real well, until I tried checkering at my workbench padded with an old towel. So much faster, easier, better I haven’t used the cradle in five years or so. In fact I don’t know why I haven’t dismantled the cradle as I’m sure I’m not going to use it again.

Yeap toomaanytools. All the years I have been checkering I used a towel or two and just held it by hand or wedge between my legs. I have been doing this for over 30 years so I guess I'm with you. Going to dismantle cradle and do what has worked for me. Thanks

My cradle is anchored by over 200 pounds of dead weight (me)

What dpcd said, you put it in a vice. Better still a swivel vice.

A lot depends on weather you use an electric tool or not. If not, you should have a sturdier setup.

I use an electric tool for spacing and my steel cradle is mounted on a Wilton power arm junior on a 3" pipe welded to a 20 inch field disk. It sits on those snap together shop floor mats you get at the big box stores.

G&H picture 1970 (George Beitzinger).
Ball Vise & wood cradle. Esso gas station shirt.