Bird Watcher:

1-On the cheap- A piece of water pipe insulation about 4" split, put on comb with duct tape. More than one layer if needed. Will give you an idea if you donot want to consider it permanent.

2-Commercial-For a non-slip surface insert a piece of non slip shelf liner between the stock and the cheek rest.

NRA: Benefactor
There's never time to do it right,
but there's always time to do it over!!