The headband is adjustable and consists of 2 sides – one for the chameleon to be attached and the other to hide all those ends.
The 2 sides are then joined with a modified 3 needle bind off. This also prevents the headband from stretching out of shape.
Lastly buttons are added to allow the size to be adjusted by about 1” (2.7 cm).
The headband itself is also easily shortened or lengthened for smaller or larger sizes than those listed. It will be about 5” (12.5 cm) wide at its widest point.

Instructions are given for head sizes 20 - 21” (51 - 53 cm), and 22 - 23” (56 - 58 cm)
These correspond to extra-small - small and medium - large adult sizes.

For the headband:
Light DK or Sport weight yarn. 100 yds (91 m)
In order to block into shape the yarn must contain at least 70% wool. Cotton also blocks well. If you wish to use synthetic fibers, then the headband needs to be reinforced with fusible interfacing.
The sample was knitted with Feederbrook Farm Entropy DK 100% wool, and Knit Picks Wool of the Andes Sport.
The front and back sides need not be the same yarn.

For the chameleon:
Use any yarn, but yarn that includes at least 50% wool will hold the shape better.
Yarn used for the sample was Four Seasons Gründl Hot Socks Cork.
46 yds (42 m) fingering weight or 37 yds (34 m) sock weight yarn

The headband is easy knitting, but the chameleon is not.
If you wish to just knit the headband that pattern is available here.
The chameleon is an experienced level pattern, using several techniques, and is quite fiddly to do.