Decide on an interesting (to you and employers) project that you can do at home.
Document through how it should work in theory, including any failure modes.
Implement it, and test it to show where it meets and doesn't meet your predictions.
Doument what, with the benefit of 20:20 hindsight, you would do differently and better next time.
Show that to an employer, who ought to realise that you love the topic, and that you have a solid engineering approach and aren't just another hacker.
Nowadays the hardware and software to do that are stunningly effective and inexpensive.