Stockroom Supply - Flat Master 18-inch (Rating: 3)

This machine works exactly as advertised.
Here is a link to their videos
Click "Build your own" then "Drum sander demo"

Pros: They claim that you can sand painted surfaces without clogging up the paper. It's true.
My third picture is a stir stick that I use to stir my poly. There are at least a dozen coats on it. There was even a large drip. The stick took 3 passes with 100 grit paper. The paper showed no evidence of gumming up or even use.
I have sanded several panels 12" wide with dust collection attached and there was no visible dust in the air and again the paper showed no signs of wear, so it will be inexpensive to use.
The surface is flat.
I bought the finished sander (Flat Master) because I was going to have to buy all the materials to build one.
When I figured the costs it was about the same for the finished unit.
If you have the materials on hand build your own the end results will be the same.

Cons: It's not inexpensive.
They say you can use 1/4 HP motor, I'm on the look out for a 1/2 HP. My 1/4 is very easy to stall.
The effective width only is about 16" because you have to be carefull not the catch the trailing end of the paper that is coming towards you.(Believe me I have done it.) They claim you can sand one half then the other with no grooves. I haven't tried it.
The top of the unit they sent me had a groove routed on the bottom for belt clearance. It was on the wrong side to the motor mount and not even close to where the belt is.

My impressions: I had intended to store this unit on a shelf and pull it out when I needed to flatten a panel or door.
I am now going to build a small bench on wheels because this thing is going to get more use than I thought.
I used some low tack masking tape around the trailing edge as a reminder to stay away and also once you catch it the end will not hold on the velcro drum. The Flat Master comes with 100 and 180 grit and I would normally never sand without going through the other grits and won't once I order them. But it did an impressive job just the same. They claim you can thickness sand with fences and feather boards.
Someday I'll have to try it. Once I find a 1/2 HP motor.
Overall I'm very pleased with the way it works.
I only gave it 3 stars mostly because of the errors in the top.