Requirements: It needed to be sturdy, flexible, removable, washable, and inexpensive. Also, he wanted curtains.
This is all of those, plus the requested curtains.
It has become a stage, a secret hiding place, a teaching tool (colors!), a toy in and of itself. Oh, and it's also a bed.
I think it might easily be modified into a playstand canopy above a couple of shelves, but I think some further engineering is required.
NOTICE: Do not use this for a crib-bed that is still in use as a crib. This design is much too low to be safe as an infant crib canopy. Also, if you want to make this for a non-crib toddler bed, you will have to create your own pattern and customize your frame.
Step 1: Ingredients
You need a sewing machine or handsewing needles and lots of time to sturdily hand sew all seams. I also used my serger to finish all raw edges on the canopy, but it's not a requirement.
A measuring tool of some kind - I used a yardstick and eyeballed anything that didn't need to be precise.
1 yard each of red, orange, yellow, green, blue and violet cotton for a rainbow, or an equivalent amount of fabric for other patterns or a solid cover.
Thread - I used black and white on the canopy. It looks fine.
3 yards of twill tape or other sturdy, non-slippery flat narrow fabric (such as grosgrain ribbon or shoelace) for ties
3 yards of 1/2" elastic
4 2 foot lengths of 1/2" white PVC pipe
6 2 foot lengths of flexible black sprinkler pipe
4 1/2" unthreaded PVC T-joints
4 1/2" unthreaded PVC elbow joints
Duct or electrical tape
1 twin flat sheet (I used the two dollar flat sheet from Ikea)
1.5 yards of blue gauzy fabric
Blue and white sewing thread
3 yards of twill tape
Mounting to crib frame (not shown):
Zip ties, heavy duty and long enough to go around the top bar of the crib.
Step 2: Assembling the Frame
To get the best curvature on your canopy frame, it should be 1.5 times the length of the crib you are mounting it to. Most cribs are pretty standard. My frame is a little over 6 feet long, and a little over 2 feet wide.
Lay out your parts as shown in the diagram.
Use PVC adhesive to secure the elbows and T joints to the PVC pipe cross pieces. Follow the directions on the can.
Apply a layer or two of duct or electrical tape to the ends of the flexible sprinkler pipe, to make it fit snugly in the PVC joints. These are not meant to create permanent joins, but snugly fitted removable ones.
Fit your parts together and test the fit of the removable pipes and add or subtract tape as necessary.
When you are satisfied, set the frame aside, but keep it assembled. We'll need it for the next step.
Step 3: The Canopy: Piecing the Rainbow
Prewash your cloth, dry it on hot. That way you have it preshrunk should your little one smear something on it and laundering becomes necessary.
Cut two 9" wide strips from each color, along the length of the fabric cut (each strip is one yard by 9"). You only need two 9" wide strips. Set the remaining fabric aside.
Finish all raw edges with a serger if you have one.
Sew two of each strip together on the narrow end. If you did not serge the edges, make a flat felled seam. If you serged, simply fold the serged edges over together and topstitch.
Take these pieced strips and sew them together lengthwise in this order: Red, Orange, Yellow, Green, Blue, Violet. Either flat-fell or topstitch these seams as above.
Step 4: The Canopy: Adding Casings for the Frame
Measure the length of the flexible pipe between the joints on the frame. Cut three casings from each of the red and violet scrap fabric pieces. Make them 4" wide and a matching length to your measurement.
Cut one of each of these in two. Hem all the short edges (I simply serged them, but I suggest a sturdier method like a rolled hem).
Fold in half to form tubes and sew these casings down along the lengthwise blue-violet seam and the lengthwise red-orange seam. Position the short casings about 1" to either side of the center seam, and the longer ones about 2" from the ends of the short ones.
Cut end casings from the blue or green fabric. These will go from the red-orange seam to the blue-violet seam, plus an inch or so, and they need to be about 7-8" wide. Hem the ends.
Mark three or four intervals along each casing where there will need to be pass-throughs for zip ties. Where these are depends on the structure of your crib. Make two buttonholes at each interval, about an inch and a half to either side of the center of the strip.
Finally, fold into tubes, and sew across the width from orange to blue. Topstitch or flatfell this seam as well, for strength.
Step 5: The Canopy: Finishing the Canopy
Hem the edges of the red and violet strips.
Cut the length of twill tape into quarters, zigzag, knot or otherwise secure the ends from fraying, and sew to each loose corner of the red and violet strips. Sew a line of straight stitches, then secure with a row of dense zigzag stitches, backstitching over the ends of the zigzag.
The next illustration is the almost-finished canopy.
Finally, cut the 3 yards of elastic in half and apply it to the wrong side of the hemmed edges of the red and violet strips. To machine the elastic on using a three-step zigzag: first set the stitch width to the maximum and the length to zero, to tack one end right about where the tie is mounted. Pin the other end to where the other ties is mounted, making sure the elastic isn't twisted. Then set the stitch length to maximum and, stretching it gently to match the fabric length as you go, sew all the way to the other tie, removing the pin before you sew over it. Set the length to zero again to tack down the other end.
The canopy is done. Set it aside with the frame.
Step 6: Curtains: Cutting the Fabric
Smooth out the fabric and cut along you fold very carefully.
Fold your twin flat sheet in half, as shown. You want two short fat rectangles, not long skinny ones.
Smooth out the fabric and cut along the fold.
Lay a piece of the blue fabric under one of the rectangles along the cut edge, overlapping by several inches to a foot. Using the edge of the blue cloth as a guide, sketch out a few cloud humps between the cut edge of the white fabric and the edge of the blue fabric that do not go closer than 1" from the cut edges. Remove the blue cloth and lay down the other rectangle under the marked one, cut edges matched up, and cut your cloud edge shape through both layers.
(not illustrated) Hem the two short edges of the blue cloth pieces. You will not need to hem the straight edges of the white cloth, as they are already hemmed.
Step 7: Curtains: Sewing
Sew a line of straight stitches about 1/2 inch in from the raw edge and remove the pins as you go to avoid sewing over them.
Finish the applique by sewing over the straight stitches and then the raw edge with a very dense, wide zigzag stitch in a light blue thread. Clip away excess blue fabric below the cloud stitches on the back of the curtains.
Sew a 1/2" long buttonhole halfway along the top edge of the curtain, about 1" in.
Fold over the edge and sew into a narrow casing, about 1" wide.
Set the finished curtains aside.
Step 8: Assembly
Disassemble the frame. Set aside the ends, and two of the black pipes. Keep the crosspieces assembled into u-shapes with the black pipes.
Slide the end pieces into the casings at the ends, then slip one of the crosspiece assemblies into the casings going towards an end piece and plug the black pipes into the elbow joints. Do likewise with the other one.
Take the last two back pipes and slip them into the split casings in the middle. Plug them into the open ends of the t-joints to complete the frame. The canopy is still fairly slack when not installed, so it should not be too difficult to do this.
Step 9: Installation of the Canopy
Thread three zip ties through the buttonholes on one end. Position the canopy over the bed, and loosely secure the ties (enough to allow some adjustment).
thread three more zip ties through the buttonholes on the opposite end. Curve the canopy into position, and again loosely secure to the bed frame.
Adjust the position of the canopy so that the canopy is resting outside the top rail of the crib on both ends, and tighten the zip ties as much as possible.
Trim the ends of the zip ties to a safe curve, do not just snip off to a hard corner or sharp edge.
Finally, pull each corner tie around each corner post of the crib bed and tie off below the top bar.
The canopy is installed.
Step 10: Installation of the Curtains
Thread the twill tape over the black pipe through the gap in the center casing. Using a bodkin or a safety pin, thread each end through the casing on the longer (inside) half of each curtain and out the buttonhole. Loop the tape around the t joint at each crossbar and back into the casing through the buttonhole, and out the other end. Secure to frame with any hitch knot.
The illustration is grayed out for clarity, and the path of the cord holding the curtains up is shown in red.