About 6 or 7 years ago, Lephantome92 raised the same question. Anermak came up with his own, original model. That thread is: viewtopic.php?f=4&t=7391
Also, I think Lephantome92 put a model in the 2010 Christmas book, which you may be able to get by designing 7 or 8 original and unpublished models to submit to the 2017 Christmas book, depending on current policy.
You can search the forum for other postings, and maybe more info about echidna models.
Note - I am not volunteering anyone for this, just providing a little history that may help or may frustrate...