Hi wayne,
matt filter is very easy to DiY.
You just need a peace of Filtermatt as big (in fact a few mm bigger is better to kep it in situ) as the side window of your tank, two smaller stripes of mat to keep the filtration matt off the pump, and a small pump equippet with a small piece of filter tube which is the water outlet from the pump.
The inlet is the whole mat. as shown in this picture.
Three tanks with mat filters