A prayer kneeler is a piece of furniture with a small shelf for books and a wooden or padded cushion for kneeling. The arms rest on the top, which may also have a small slant and edge to hold a book.
Choosing the wood. Look at the kinds of boards available and chose something that appeals to you--oak, maple, cherry, alder, ask, birch, pecan.
If you don't have the right kind of saw, you can describe the cuts you need at the lumber store and they can make all the cuts for a small additional price.
After you have the two sides of the prayer desk, choose the outside by the grain you find most attractive, as the inside won't be seen as much. Make a template with a piece of paper, and use it on the inside of each side to mark where the dado joints will go. It is important to flip the template so the two sides are mirror images of each other. Cut out 1-inch deep dado joints with a router, hammer and chisel, or by sawing with repeated cuts until you reach the exact size to hold the bookshelf lumber. You can always make a cut a little wider, but never narrower. Measure two or three times, cut once.
After cutting the bookshelf dado joints with the router, make cross lap joints where the prayer desk sides join the two runners. Make the cross lap joints so the runner is on the inside of the joint and the facing of the sides goes from the top of the desk to the bottom.
Make a cutout 2 inches deep and 12 inches long on each runner to place the kneeler, 3 inches from the end. Add glue and clamp the kneeler in place. Let dry overnight.
Attach the bookshelves in their slots to the sides of the prayer desk with glue and clamp with a belt clamp. Use rubber mallet to tap them in.
Glue the sides to the runners and clamp. Drill starting screw holes on inside of runners, and screw 3 wood screws on each runner to hold securely to the side.
Finish with oil or any finish you choose.
Many people prefer a pillow or cushion on the kneeler if they will be using it a lot.