Who devises equipment for the Rehabilitation Center?

In The Giver, children are required to serve volunteer hours when they become eight years old. They have the freedom to choose where they serve these hours. Jonas remembers how many of the Eights begin their volunteer hours serving Recreation Duty because it is familiar to them. Soon they will begin serving where their interests and skills take them. The Elders watch the children as they serve their hours, in an attempt to appropriately place them into a career during the Ceremony of Twelve.
A boy in Jonas's age group, Benjamin, spends most of his volunteer hours in the Rehabilitation Center where he works with injured citizens. Jonas recalls how Benjamin worked to develop "some machines and methods to hasten rehabilitation." Jonas feels certain that during the Ceremony of Twelve, Benjamin will be assigned to the Rehabilitation Center by the Elders.