I made it for the Male Room Challenge: anything goes with the option of origami.
For my card I traced the lines from the pattern onto white card. then cut along the lines and fold them inwards or outwards.
I like this design particularly as it looks like two staircases in different directions, like an Escher painting.
I adhered a piece of dark purple card on the back and stamped the Happy Birthday from Simon Says Stamp It's your birthday set with Versafine Clair ink.
It fold almost flat, so it will go in an envelope.
For more information on the Male Room Challenge, see this.