sci-fi/fantasy book with time distorting box?

[Tech3599]

sci-fi/fantasy book with a box that speeds up time when you put your hand in it, causing one guy who used it to be younger than he shoud be. There were also some small creatures or something in the box.

P.S. it says flowers for algernon in this post because I couldn't avoid putting something in that stupid box. If I knew the title to the damn book, I wouldn't be here.