Most of the ones I make are sleeve that slip into the carb but much of it would apply to making one to put on your petcock. 100 mesh screen (100 holes per inch) is what I use as it is common on the motors I have although I have found larger mesh (lower number) in larger motors that have a screen filter. I will cut a piece the size I need then roll it up tighter than I need. Then I slip it over a drill that is the size I need. I put just a little soldering paste on the joint. Then with just a little solder on the tip of my gun I wipe it on the joint. Short video link below. There is also a link to a supplier on eBay from China. As best as I can determine you would want the 80 mesh. You’ll need to do some adapting to close the end and solder it to your petcock, along with the tools you have, but this may give you a place to start. Video Link – https://youtu.be/lPOkIXm7C1Y Supplier link – https://www.ebay.com/itm/176504459596?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=8VyfVyPZTg2&sssrc=2047675&ssuid=_-YLkpExSsW&var=476097754116&widget_ver=artemis&media=COPY
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.