In advance: Make cloud topper. Add 1/2 teaspoon Gum-Tex to 4 oz. white fondant; roll out 1/8 in. thick. Using patterns, cut one each back cloud, right cloud and left cloud. Let dry overnight on cornstarch-dusted board. Attach two left and right clouds to back cloud with thinned fondant adhesive; let dry. Attach two lollipop sticks to back, leaving 2 1/2 in. extended. Also: Prepare and cover base board with 18 oz. green fondant.
Bake and cool 2-layer cakes. Prepare for Stacked Construction. Prepare and cover cakes with 54 oz. blue fondant. Tint 18 oz. fondant green, 4 oz. brown, 2 oz. darker green, 2 oz. black, 1 oz. gray; reserve some white. Roll out 1/8 in. thick. Using patterns, cut out hills, tunnel, trees and bushes; cut additional free-form bushes. Cut clouds using smaller cloud patterns, trimming to fit as needed. Attach with damp brush. Cut letters using Cut-Outs; attach to cake and topper with damp brush. Cut a 1 x 2 in. green piece for candle track base; attach using rotary cutter. Cut 50 track ties, 3/8 x 1 3/4 in.; attach to candle track base and base board, 3/8 in. apart. Assemble cakes on base board. Cut 1/8 in. wide gray strips for rails. Attach over ties with damp brush. Position candle and insert cloud topper.
* Combine Kelly Green with Lemon Yellow for green shades shown.
* Combine Brown with Red-Red for brown shown.