I went with Lycra for the costumes, 'cause that's what superheroes costumes are made of. I reused the Scuba Hood pattern from Brindelle and Twig that I used for the Ewok costume for the top and hood, with a few additions. For the leggings I found this free pattern on Craftsy. Given I only have boys who don't really wear leggings in their day to day ensembles I didn't want to buy a leggings pattern. I also bought maskerade masks in blue and green.
I bought the right shades of blue and green for the main fabric. I got electric blue and green for the accents, but it turns out the characters only have the electric colours for a piece or two, and they are are a darker shade for the accents. Oops.
I mostly followed the patterns with a few tweaks. For Catboy in blue I easily had enough fabric using 1.5m of a 1.5m wide bolt. I had to be a little careful with the pattern placement, but still had enough for Gekko from 1m of the 1.5m wide bolt. However I did stuff up with my Gekko costume, as I folded the material the wrong way before cutting. There was enough stretch that it was a not-disastrous mistake that required the buyng more fabric.
Customisation for Catboy:
An appliqued mask on the front, backed with double-sided interfacing before stitching.
Once I had made the outer of the hood I tried it on Sprog, then placed a piece of paper across his forehead and traced the edge. This was the basis for a little piece over the forehead to cover the difference between the hood and the masks. I layered this into place before sewing the inner and outer of the hood.
Ears. I cut triangles, stitched the edges on two sides, turned them right side out and top-stiched a little under a cm from the edges. To attach the I cut slits in the outer layer of the hood, tucked the ears into place and pinned them. I topstitched as best I could, but don't look too closely. It was tricky and a bit messy.
The other factor was the stripes. These I painted on with fabric paint, which needed to be set with ironing. To start with I did it freehand, then I realised that masking tape was the key to crisp lines. To paint the lines on the hood I filled it with a ball to keep the shape, before painting.
A tail. this was a long tube with a rounded end. I stuffed it with the insides of a pillow that cat had attacked and hand sewed it. The end was sewed around edges in a circle rather than sewed flat into the seam.
Customisation for Gekko:
An appliqued mask on the front. I did it upside down the first time. Oops. I cut it off the front and recut a front piece and sewed the whole piece on as one rather than redo all the little applique.
Oops upside down Gekko!
The other distinguishing features of Gekko were the tail and fins on the head. The tail was shorter and a bit pointy, but otherwise done the same as Catboy's.
The hood had the same forehead covering, but before assembling the outer layer I added fins. To make the fins I sewed triangles into the bright green fabric, then added interfacing to each side and trimmed the excess before turning it inside out. I stuffed it with some more pillow inner, then closed the seam. The completed fins I then pinned into the hood before sewing the assembly seam.
The final addition was padding. Gekko crawls up the sides of buildings and has grip on his hands, shoulders, elbows, and knees. I cut that from fleece from a previous project, and hand stitched it on.
The boys were very pleased with the final product and wore them all day, though the masks came off within an hour or two. For the final touches I put blue or green tape over their shoes.