Most staircases have some kind of newel caps on the newel posts.
I can make replacement newel caps for your staircase. Perhaps they were removed by a DIY enthusiast in the past. Ask a neighbour if their newel posts are complete, take a photo and e-mail me the digital image, J-Peg preferably, and I will let you know how much, or little, it would cost for me to make a replacement cap for you.
I can also make caps with a more unusual design. What do you have in mind?
Quite often the same design can be made in pitch pine, scots pine, oak or mahogany. The same design can also be made bigger to suit larger posts. Not all designs, however, work in a smaller size.