From Muppet Wiki

The Evolution of the Tommie puppet (1976-present)

Image	As seen in	Year	Notes
	Sesamstraat Season 1	1976-1977	The first Tommie was designed and built by Ton Hasebos. For the character, he used an old fur coat. The puppet was performed with arm-rods. This version lasted for the first season only.
	Sesamstraat Season 2	1977-1978	The second Tommie was also designed and built by Ton Hasebos. His eyes are changed to make him look less angry and the puppet was no longer performed by arm-rods, but was a live-hand character instead.
	Sesamstraat Season 3	1978-1982	This version more closely resembled a dog. His eyes were round and yellow, and his nose was more like today's version. He still kept a stuffed-animal look instead of a Muppet-inspired design.
	Sesamstraat	1982-1990	Tommie is redesigned for the first time by CTW and the Muppet Workshop. He lost his teddy bear appearance and looked more Muppet-like. A mustache and eyelids were added, and the character began wearing all sorts of things on his head.
	Sesamstraat	1990-2005	A slightly updated version of Tommie is made. More facial hair and a slightly dark fur were the most prominent differences, along with a change in his head shape to make him look younger.
	Sesamstraat	2005-present	The color of his fur changed to a warm brown and more facial hair was added.