[WANT TO LEARN MORE GREAT TECHNIQUES LIKE THIS? GRAB A COPY OF MY E-BOOK]
This is a great trick for quickly making clean lines in EVA and require no dremel or power tools.  This works wonderfully for precise machine lines, or other decorative details.  All you need for this is…

Get your piece assembled and ready for the detail lines.  I’ve cut out a random shape here and drawn on some decorative lines.

Taking your X-acto knife, start at the corner or edge of a pattern.  Carefully score on the guide line, you don’t want to go all of the way through, only about 1/8 of an inch deep.  Also a word of caution, when cutting a line and you come to an edge or corner, stop just a little bit before finishing the cut, turn the piece around and star cutting from that corner and connect the cuts.  This way you will not risk over cutting and mess up you lines.   There is no way to really fix this if you screw up, so be careful.  Also, don’t cut with a sawing motion, if you have to do this, then it means your blade is dull and needs to be replaced or sharpened.

Now for the fun part!  Using your heat gun, go over the lines that you just scored.  Don’t stay in one area for too long or else you will burn the foam. Be sure to keep the heat gun moving and don’t hold it too close.  You’ll start to see the lines pop open.

If you notice a few lines that are not connected, just carefully go over those areas with your x-acto, re score them and hit it with the heat gun again.

Next add your paint and a little weathering, and tah dah!  Amazing and simple detail lines!  I used this same technique to make the new armor and necklace worn by Rana-the face of Samara and Morinth.  If you’d like to try out a quick easy project using this technique, grab the Samara Choker patterns and give it a go.

For more great costume and prop making techniques check out my e books on foam firearms and painting.

Happy costuming!

-WM