For both my Photoshop final designs, I took a shape from a mid-century item and designed a pattern using that shape. Here you can see the development of the designs.
The first design I created in Photoshop was based on the dial of a mid-century telephone. After a one colour design was first created I played to come out with the design that includes all the colours.
The second design was based on a mid-century radio. I experimented with shapes that featured on the radio and kept it to small, simple details.