An oscillating sander is a good for controlled fine sanding. The best way I can think of is similar to sanding drywall. You would not use a belt sander for drywall. Also, the drill helps to get the proper speed you need.
The base will be 5 1/2"x 17 1/2'. The guides will be 12 1/2" inches in length. They will be screwed onto the center of the base. There will be 2 1/2" on each side of the base. This will help when clamping the unit on a workbench or table.
Maple is used for the guides and the rail. They are all cut at 20 degrees and fit together perfectly to make a smooth slide system.
This piece will be for the support for the shaft and wheel. A metal sleeve will be added to help reduce wear on the wood.
A second hole is drilled for a pin. The pin will be screwed into the wheel and will fit in the slot to move the slider.
See the video build here.
The slider will consist of a frame mounted on the rail. The slot will be for the pin on the wheel to move the slider back and forth.
An aluminum rail will be added to help keep things slick. I found a piece in my junk bin and cut it to size, the same length as the guides. I took a piece of fine steel wool and cleaned it up a bit.
I used my Angle grinder holder to cut the aluminum to 12 1/2" in length. It will be screwed onto the base. Two small screws one on each end will do.
Here is most of the pieces put together, it still needs a top and sandpaper.
A top is made from a block and screwed on. Slots were cut on both ends, this will be for the sandpaper block to snap on and also for a screwdriver to fit in for the screws on the bottom of the slider.
The base is 2 1/2 inches larger on each side so it can be clamped easily on any table.
Here is the bottom of the sanding block. to make the sanding blocks two dowels are glued in, they match the slots on the slider and snap on very secure.
The sandpaper block is very simple to make and replace. After testing I was very happy with the sander. I will make many more sanding blocks with different grits and am sure I will get lots of use from it.