I recently found some cool flashcards to help folk learn either Hiragana or Katakana:
Each set is £10 including postage in the UK (they probably ship internationally though).
I personally picked up a set of the Katakana cards as it’s something I don’t see or use as often, and it slips my mind constantly - so having a refresher is nice.
The cards themselves have nice visuals and are well made so it might be helpful to someone. The only criticisms I have are that 1. The sounds and visuals don’t always match up with how I naturally expect (but they work better in relation to the Japanese, if that makes sense), and 2. I wish the images were on the back rather than the front for revision purposes.