What burnisher should I get for a card scraper?

A smooth, hard, round steel shaft can do the job, including a suitable screwdriver shaft. If it slips or gives inconsistent results, a dedicated burnisher can make the process easier to repeat. Before turning the edge, file the scraper flat and square. Getting a useful hook still takes a bit of practice.

If you want fewer variables, a guided burnisher can make setting the hook more straightforward. That convenience costs more, though, and it isn’t essential. I’d start with a decent basic burnisher or a smooth, hard rod, then consider a guided tool if getting a consistent edge is the part that keeps frustrating you.

Think of the scraper as a fine surface-cleanup tool, not a way to reshape the work. It can help with localized tearout, raised grain, glue residue, or smoothing figured wood, and it can be handy around veneer or small inlays. For grooves and some curved or awkward spots, sandpaper may be easier to control. Scraping can reduce sanding, but it doesn’t have to replace it everywhere.