Yeah make one out of an old (large) paint bucket with lid be sure to get all the paint out first using standard plumping pvc fittings and some suitable flexible tubing with jubilee clips.
water is pumped into the top via lid, flows throw filter medium out the bottom hole back into the pond
( I put an overflow pipe near the top which indicates when the filter is clogged and needs a clean) works very well filter media can be gravel ,stones and some of the fluffy stuff from an old pillow or duvet which will clog up quite quick but just take it out wash it with some clean water with a hosepipe every so often stuff it back in put the lid back on....you might also want to look at a cage/filter to stop the pump getting clogged up and burning out if it runs for a long time with little or no water flow to cool it.