It's been a few years since I've been there but I the thing I remember most about Capelli's is how expensive they are, but it's a nice walk from Loew's, if they're still open. As for the other shops you list:
A.B. Charles and Sons;
never heard of it
Herb's Hobbies in Doylestown;
> Penn Valley Hobbies on Main St. in Lansdale;
both over an hour or more from downtown, though I've never been to either.
Leisuretime Art, Craft and Hobby, 325 Bustleton Pike, Feasterville
Mostly crafts last time I checked, not worth the trip. Al's (or Allied) hobbies is a well stocked shop located in northeast Philly, about a 30 minute ride from downtown. If your in the neighborhood it well worth stopping in but I wouldn't make a side trip to see it. Especially not with all the great stuff to see within walking distance. Heck, if he like machines, tell him to take the ferry to Camden and visit the Battleship NJ. HTH Gary