The basic form “door” Share on Facebook Share Share on TwitterTweet Share on Google Plus Share Share on Pinterest Share Share on LinkedIn Share Share on Digg Share 1. Fold a square sheet in half and develop. 2. To the planned line fold lateral sides. 3. The basic form “door”. If you have found a spelling error, please, notify us by selecting that text and pressing Ctrl+Enter. Share on Facebook Share Share on TwitterTweet Share on Google Plus Share Share on Pinterest Share Share on LinkedIn Share Share on Digg Share