Free plans work if you are an intermediate woodworker who can "fill in the blanks." Beginners should invest $10-$15 in a plan from a tested source like Etsy (look for 4.8+ star ratings) or a woodworking magazine.
The vertical structure that connects the base to the top rest. The Armrest/Shelf: diy prayer kneeler plans work
At the top of the slope, there should be a small lip or a recessed shelf (about 1.5 inches high) to hold a prayer book, rosary, or tablet open. Free plans work if you are an intermediate