Run, do not walk, to a store (hardware or woodworking) and get one of the paint scrapers that hold the blade on with two screws "Pro-something or other". You want to scrape while the epoxy is green, 24-30 hrs with System 3. The epoxy feels hard but if you put your hand on it and press, there is a slight tackiness. After the epoxy hardens more, your work effort goes way up and so does the itch factor. Get the blade that is not quite a square, about 1 inch wide.

Scrape the edge of the tape until it is smooth and tapers into the un-taped area. It helps to sand the tape edge first (60 grit) just to get a flat surface that doesn't catch the scraper edge. It also helps to blunt the square corners so you don't gouge into the epoxy in the un-taped area. Vacuum regularly to keep the area clean.

When you have the tape edges done, then go over everything lightly with the scraper. This knocks all the high points off and the next coat is smoother.