Printables
Katakana Practice Sheet
Stroke-order practice grid for the katakana syllabary.
Short answer
The same stroke-order grid for katakana. Worth practising separately from hiragana, because several katakana differ from one another mainly in stroke direction rather than in finished shape.

What is on the sheet
A stroke-order practice grid for the full katakana syllabary, laid out the same way as the hiragana sheet: one full-size reference character, faint guides to trace, then empty squares.

Why katakana is worth practising separately
Katakana is angular where hiragana is curved, and several characters are easy to confuse with one another — the pairs for shi and tsu, and for so and n, differ mainly in stroke direction. Writing them out is the most reliable way to internalise the distinction, because the difference is in how they are made rather than how they look.
How to use it
Work through a row at a time. Since katakana is used mainly for loanwords, practising with names you already know gives immediate feedback on whether you have the character right.
The four characters everyone confuses
シ and ツ, and ソ and ン, are the pairs that cause trouble, and they cause it because the difference lies in how they are written rather than in how they end up looking. In each pair, one character's short strokes come in from the side while the other's come down from the top; the finished shapes are close enough that reading alone will not reliably teach you to tell them apart. Writing them will, which is the strongest single argument for practising katakana by hand rather than by recognition.
Practise with words you already know
Katakana is used mainly for loanwords, names and onomatopoeia, so almost any learner already knows dozens of words written in it before starting. Working from those rather than from isolated characters gives immediate feedback: if a character is wrong, the word stops being recognisable and you notice on the spot. Isolated character drills provide no such signal, which is why they feel productive while quietly allowing an error to be practised in.