Many of us buy a rifle and mount a scope on it, only to find that the comb of the rifle is too low to properly look through the scope. We need a cheek riser. Proper cheek weld is important to your marksmanship and there's nothing quite as aggravating as having to move your head around to see through the scope. There are several ways of curing this problem, and you can find stocks that have adjustable combs, you can buy add-on cheek risers, or you can make your own.
Being the frugal sort of guy that I am, I looked around at locally available items that might suffice. The first thing I found was an elastic buttstock ammo holder. These things normally hold nine rounds of rifle ammo and can be found in any of the big box stores, normally for under $5.00. All by themselves, they're a worthy addition to any hunting rifle, and I normally pick up a couple a year. Someone is always needing one, and I try to keep several extras on hand. That's half of the answer to a cheek riser.
Because the ammo holder is elastic, you can put something under it to raise the comb of the rifle. I like to use common pipe insulation, although even a child's swim noodle would suffice. In the photo below, I've cut up a piece of old swim noodle to demonstrate.
**UPDATE** I posted my handyman fix on a forum, and a commenter led me to the Beartooth Comb Raising Kit. At $22.95, this looks like a good, inexpensive fix. It's remarkably similar to my cobbled-together cheek riser. I may have to buy one to try.