Rather than have a straight line between the carpet and laminate flooring I want to create a half circle shape where the computer chair goes, so that the wheels on the chair do not go onto the carpet - just to give a bit more moving space by the computer.

There used to be a vinyl strip that was used in the hotel industry when I worked for Residence Inn's.All joined areas between the tiles or laminate flooring was joined by these.

BUT!

If you would rather a different idea.I use a piece of Masonite board to protect the tile floors under my chair,it would work the same on a carpeted floor,you just need to make it large enough for your freedom of movement.

A 4X8 sheet doesn't cost all that much and cutting it with a jigsaw is simple also.Sand the edges,etc..

Just a thought.

Seriously doubt that you will find such a thing. Are you talking about something permanently attached to the floor or something just attached to the laminate which is just laying on top or the carpet.