I've been asked to upload this minor modification to the great wade extruder linked herein. What I've done is put an island on the 'top' (which when the item is placed upside down is now the bottom) that allows a screw-in push-fit connector to be placed for guiding the filament 'down' and attachment of PTFE tube to the extruder. I have also made a 'plate' which allows another push-fit connector to guide the filament from the top into the extruder, and allow attachment of the extruder base (now the top!) to the frame of a 1515 openbeam type frame. The tilting screws fit nicely around the new 'island', but you will need to manually cut off the tongue part of the pivoting mechanism which previously pushed against the filament. It's no longer needed, and I haven't bothered to edit the STL.
Print the STL which gives you the major parts of the extruder body. You will NEED to print this with support, as I have had to put in overhang for the push-fit island. Cut off the 'tongue' of the pivoting part which pushes the filament; this no longer fits, as the 'island' is in the way. glue/screw push-fit connector into the island, for feeding filament. Also, attach PTFE tube to the push-fit. There is a base-plate which converts from the current 'base' to allow attachment of a 2nd push-fit, and screw to 1515 beam; this will follow ASAP.