A shopmade splitter
Most woodworkers understand the importance of a zero-clearance insert and either buy blanks or make their own. To add a splitter to one of these inserts, I just glue a piece of wood into the slot behind the blade. The splitter stock should be the same thickness as the blade and should fit in the mating slot the raised blade cuts in the throat plate. The splitter is most effective when it is placed closest to the back of the blade. Because the blade progresses toward the back of the insert as it is raised for thicker cuts, I suggest at least two inserts--one for cutting thin stock, up to about 1 in., and another for thick stock.
To make an insert for thick stock, you must elongate the slot by flipping the insert end for end and then raising the blade. This allows you to place the splitter farther back on the insert. I always drill a finger hole in the insert for easy removal. A short adjustment screw can be embedded into the side and/or end of the insert to take up any play in the fit, and the splitter can be sanded.
The important thing is to align the right edge of the splitter with the right side of the blade (the side closest to the fence). This keeps the workpiece against the fence for a smoother cut. Also, it virtually eliminates the chance of kickback.
I make the splitter by slicing a piece of hardwood and trimming it until I get a tight fit in the slot. Then I glue it in place. I make my splitters out of hardwood, but there is no reason why they could not be made of aluminum, plastic or any other durable material.