http://enigma-replica.com/index1.html
https://www.cia.gov/news-information/blog/2016/who-first-cracked-the-enigma-cipher.html
https://hackaday.com/2016/10/21/3d-print-an-enigma-machine-thats-close-to-the-real-thing/
https://www.pinterest.com/search/pins/?q=enigma%20machine&rs=typed
http://www.instructables.com/id/Make-your-own-Enigma-Replica/
http://cryptocellar.org/Enigma/http://www.matematiksider.dk/enigma_eng.html