Someone made me a pincushion and she used wool. I don't know if it keeps the pins sharp, but I believe the lanolin in the wool prevents the pins from rusting. It is my favorite pincushion. She used a small round aluminum kitchen mold for the base, and glued the outer fabric inside the rim. The only other pincushions I use are magnetic. I like them a lot, and prefer to take one of those with me to quilt somewhere other than at home. The pins don't fall off in traveling.