Gift ideas -- art, literature, books for children; Three Bears dimension; Goldilocks and the Three Bears: A Fold-Out Book, illustrated by Martin Baynton, design by James Roger Diaz and Sandra Tiller. New York: Lothrop, Lee & Shepard (pages not numbered). $6.50.

Little children will enjoy this charming version of Goldilocks, contained in the shape of a small, sturdy paper house.

The outside of this three-dimensional cottage is decorated in true storybook fashion, promising a surprise within. The house opens in half to reveal, on one side, the interior of the bear's cottage, complete with a sleeping loft and pantry.

The book itself folds out in accordion-like fashion from the other half of the house, ending with a vignette of Goldilock's escape.

This fully illustrated story-diorama combination is delicately detailed and full of treats for a child's eye. ''Goldilocks'' and three new companion classics by Lothrop, Lee & Shepard, all done in a similar style, would make a nice decorative addition to a shelf as well as favorite bedtime fare.