>> Sure, they're quite common. Just Google for "constant force spring".
>
>Thanks... knowing the right term is worth a lot :)

The sort of thing you are after is surely those "hang from roof" things they
use for small power tools on production lines. Not sure that they are not
much more than a long soft spring of appropriate tension for the weight of
the tool, and doesn't take a lot of pull from the operator to pull it down
from the equilibrium position to the work piece.

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