While we are talking about model boat building, a tool that has proved to be unexpectedly brilliant is the Microzip hand sander.
On the face of it, the tool appears just to be a foam handle to which various grades of sandpaper are attached with velcro fastening. It turns out to be superb though - good enough that my aged parent wants to buy another one so he has a spare.
The handle is very comfortable to hold and affords excellent control. While the foam is slightly squashy, the 9cm long sanding area stays flat unless you push it hard.
Basically, someone got the ergonomics very right indeed.
Price including sanding pads, just under 8 quid from S&M Tools. (Yes, I know that sounds dodgy but it is safe for work!)