How do you sort a set with no instructions?

[ficbot]

My four-year-old stepson was here for a week and made a mess of the Lego :) It's fine; we wanted him to play and have fun, and I love that unlike his same-aged cousin, he can build without instructions and use his imagination. Now, I want to put things back though. And I am wondering what to do about sets which don't have instructions.

For instance, he has this red construction box which comes with an 'idea booklet.' You have to take apart the one idea to build the next one. Short of building every idea in the book, I am not sure how I can determine which pieces belong to this set.

The reason I want to part them out into sets is that I have found with him, he likes to take apart things. I think he is not comfortable yet with a big pile of pieces. But if he sees a cool build he likes, he will take it apart and improve it a little. My camper van got demolished for example because he took it, played with it for awhile, and then decided he had to take off the door so that the robot wings would fit. Since this is how he seems to play, I am hoping that if we can put together some of *his* stuff for him, he'll take that apart and leave my husband's Ghostbusters car alone :)

So my goal is to try and return as many of his pieces as possible to his own bin, pick out the stuff I think he borrowed or stole from others, return them to their origin places, and be left with only his stuff. Problem is, a few of these sets are general piece packages and I am not sure how to determine their parts collection. Ideas?

[Sinthoras]

You can go to brickiest.com, search for the set number, go on the set's entry site and click on "parts", there should be an inventory list.

Edited July 26, 2015 by Sinthoras

[Peppermint_M]

Bricklink also has a parts list for any set (including spares) The booklet or box should have the list of parts anyway, but if these are lost then you can't go far wrong with Bricklink.