I made this robe out of a 140 x 70 cm bath towel. I managed to arrange my pieces so that I could use the finished edges of the towels as hems at the bottom, along the sides of the front panels and as sleeve hems. I just made the pattern pieces up when I went along, but did write down the measurements. If you would like to recreate this robe, here is a cutting diagram.
The sewing is pretty straightforward. I didn't plan on making a tutorial, so no pictures here, but just sew the following steps; align the front and back pieces (right sides together) and sew the shoulderseams.
Place the body so the right sides of the front and back are facing you, lay the sleeve on top (right sides together), make sure you line up the center of the sleeves with the shoulder seam and that the finished edge of the towel is your sleeve hem. Sew the seam and repeat for the other sleeve.
Next step, start at the sleeve hem en sew the sleeves and side seams of the body closed in one go (right sides together).
Now you're done with the body, time to start on the hood. For the sideparts of the hood I used an additional guests cloth 50 x 30 cm. The hood is lined with a white fleece blanket I spotted on my way out of the big blue and yellow store (just cut the same measurements as the main hood).
The hood consists out of three pieces. Sew the sides of the hood to the middle stripe, right sides together, repeat this for the lining.
Attach the hood lining to the main part by arranging both hoods with the right sides together and sew around the front.
Arrange the hood around the neckline with the outer hood facing the robe's right side and sew the seam. For a neater finish I've sewn some bias tape over this seam.
I also used the fleece blanket for the belt, 125 x 10 cm, sewn in half lengthwise. and reused the twill tape tabs from the towels as belt loops. These are sewn over the side seams, it's best to put the robe on your kid to see where you want the belt to go and attach the belt loops at that height.