SOLVED. Child's Chapter book: the hammer makes things grow or shrink [s]

[Melissa]

I'm trying to find books I enjoyed as a child to offer my son. All I remember about this one is that a boy (I think) got a box of toy parts and tried to put a car together only to find that the wheels were all different sizes. He hit the wheel with the hammer that came with the set to try and make one fit, and it grew (or shrunk) but became the right size. He discovered that he could hit things with one side of the hammer to make it grow, and the other side of it to make it shrink - and it worked on him, too. (I think.)

I can't remember what else happened, but it would have been published before 1995 or so, maybe an inch or half-inch thick paperback chapter book.

[bookel]

One of the Ruth Chew books?

[Holly]

bookel wrote: "One of the Ruth Chew books?"

I think you might be right. Sounds like Do-It-Yourself Magic.

[bookel]

Yes. They're all so similar I couldn't think which title off the top of my head. :)

[Melissa]

That's it! I remember the castle on the cover. (I was ordering the Castle in the Attic when this story got knocked loose in my head, so that makes sense.)