Ho-lee Smokes! How does any plastic scale modeler, especially aircraft I would think, live without this sander? I ran across it while ordering at Model Paint Solutions.
https://modelpaintsol.com/model-paint/david-union-du400-pencil-style-electric-sander
I am currently working on the old Hasegawa 1/72 Blue Angels kit with the six aircraft that I started back in 1989. (A lot has changed in modeling since then, LOL). I had a heckofatime fitting the Cougar fuselage halves and then also the wing assembly to the fuselage. I was left with some very unhappy offset seams. The task of dealing with this by hand sanding was the stuff of nightmares. Before tackling it I ran across the description of this sander at MPS's website so I went for it. It is freaking amazing. The worst seam offset was at the rear of the bottom of the wing where it connected with the anterior fuselage. I had filled the offset several days ago with Vallejo putty. I began sanding with the new tool and I prolly spent a little over an hour taking the overbite down from one side of the wing to the other. Hand sanding would have taken me forever and resulted in loss of surrounding panel lines. This tool was a dream. Later sanding the main top and bottom fuselage offset seams that I had filled with Mr Surfacer 500 was, with this sander, an amazing experience. You can precisely control the sanding area without encroaching on surrounding details.
You gotta check thing out! It's The Bomb.
BTW The well cured Vallejo putty sanded really, really nicely. And Mr. Surfacer as a filler sands like a dream.