Freezer paper - sold by the metre.
I have read about this stuff and must admit I was a bit sceptical - but it really is truly a-may-zing! Just iron it to your embroidery fabric, cut it to A4 size, then put in your printer (probably face down - but test first) and print out your pattern. Then you just peel off the paper and you're all good to go. Brilliant! Perfect for small projects. No messing about with carbon paper or tracing. Also an awesome product for quilting and scrapbooking.
I have tried it with both calico and linen - both worked a treat!
This only works with ink jet printers and it's not permanent. THE INK WILL RUN if you wash it so it's not suitable for embroidery projects which you plan to wash. I have tried soaking the printed fabric in white vinegar then rinsing in cold water. This definitely stops some of the ink running but there is still a wee bit of bleed. I just embroider over this but it's worth bearing in mind. If you think you will be washing your pieces, you can buy a product online called Bubble Jet Set - you soak your fabric in this and it stops the ink from running.