A 6th-grade boy's favorite denim jacket had got holey and frayed in the back. Ambrosia got a hideous glow-in-the-dark heavy metal t-shirt I'd bought satirically for three quid in Swaffham Market (Norfolk, England), and cut out the best bit. 

The secret to success here was extremely careful cutting with the tiny scissors: it's great because of the detailed outline. Then Ambrosia spray-glued the beast on the back. The glue washes out but you need a piece this big and awkwardly shaped to stay put while you work. (She could have used fusible webbing but we didn't have any around...) Then she tacked it invisibly with pick stitches in matching black and white threads. Then sewed accurately all around the edges in a beautifully even and decorative blanket stitch. 

And don't forget the moon. The moon is important. 

Her son has not removed it since the day it was bedragoned. 

Techniques:

Accurate cutting

Cheating glue 

Or fusible webbing

Invisible tacking

Blanket Stitch