Lay out your two-by-four boards and measure two 55-1/2 inch pieces and two 28-inch pieces. Draw out the lines with your carpenter's pencil as a guide.
Set up your guides on the table saw and cut the pieces along the lines.
Construct a box with the four pieces, placing two deck screws into each corner. Countersink the deck screws with your power drill.
Lay out your 2-inch-by-8-inch boards and measure four 28-inch pieces. Mark the lines with your carpenter's pencil as a guide.
Cut the pieces out with your table saw.
Position the pieces inside the box with two at each end and the other two spaced 18 inches from the sides. Fasten the pieces so that they are flush with the bottom of the frame. Screw them in with countersunk-deck screws placed every 4 inches along the sides. Also, attach the two side pieces directly into the sides of the frame for extra support.
Print off the coloring page of Thomas in the Resources section of this article and take it to a print store to have the image enlarged. Ask to have it blown up to a height of 3-1/2 feet and printed onto cardboard.
Cut out the train and trace its shape onto one of the plywood sheets. Cut out the train shape with a jigsaw, working slowly to get each curve.
Cut apart the coloring page into stencil-type pieces for each line and change in color. Trace each individual piece onto the plywood to draw the train.
Paint the train, matching the colors on the original coloring page with the wood paint and sponge brushes. Allow the paint to dry completely.
Cut the other plywood sheet to 54-by-28 inches to fashion the mattress support that will lay on top of the frame on the completed bed. For easy removal later, don't attach it to the frame. Set this piece aside.
Take the remaining two-by-four board and cut two 27-inch posts and two 20-1/2 inch posts. These will be the top and bottom posts of the bed.
Fasten the posts onto the corners of the bed using two countersunk screws where the legs meet the frame.
Cut one two-by-four piece to 31-7/8 inches to make the headboard. Secure this to the head of the bed 1 inch from the top with finished nails placed every 4 inches.
Center the Thomas cutout on the foot of the bed and nail the image to the two foot posts with nails placed every 4 inches.
Cover all screws with wood plugs and cover all nails with wood putty using a putty knife.
Sand the edges of the wood along the bed with sandpaper and a vibrating sander until smooth.
Paint the rest of the bed blue and let it dry.
Apply a coat of lacquer over the paint to give the bed a gloss finish and added kid-proof protection.
Place the mattress support into position and put a mattress onto the support.