If the hard wood pieces are not already prepared, cut them out to specification using your jigsaw.
Take two of the boards and cut them down to 10-11-inch widths and 1 1/4 inches. Glue the panels together and use clamps to hod them in place until the glue sets.
Draw a two-inch circle on each end of the rails to mark their tenon sizes. Measure up 7 1/4 inches from each of these ends and draw a circle to mark the tenon length.
Use your jigsaw to shave out the tenons on the end of each piece. You should end up with pieces that look like rolling pins. Do this 16 times. Sand the pieces smooth when done.
Use a 2 1/8-inch self-feed bit to drill 16 holes in the four posts you will be using for the crib. Measure up 14 inches and 38 inches respectively from the bottom of each post to mark the hole centers. Rotate the posts 90 degrees, then measure up 10 1/2 inches and 41 1/2 inches to mark the second set of hole centers. Drill the holes when done.
Use the masking tape to mark exactly how far down each post will go down into the holes. Mark with the masking tape on both the posts and the rungs.
Drill down to the depth-line you created with a 1 1/4-inch drill bit.
Sand the ends of the rungs to a 1 1/4-inch diameter so they will fit into the holes.
Glue the rungs into the holes one at a time, then allow to dry for 24 hours. Make sure that each piece square and level before continuing.
Mark where each peg will be placed on the crib on the post with a pencil.
Use a 5/8-inch drill bit to drill the holes on the post where the pegs will enter. Sand away each hole until the pegs fit.
Put glue in each hole, and place the pegs in. Allow to dry.
Sand the crib until it is smooth.
Stain and paint the crib to how you like it.