Huh, I was googling last night and nothing. I only find one Latvian site, and there I found that Mr. Juris Grinbergs made replica of I-12; but there is no contatct of him. There is only contact to website owner:
" CONTACT INFORMATION
The owner of this website is Gunars David Zulis.
I can be contacted at Zulis@aol.com
I encourage and welcome feedback, factual corrections, or offers to contribute to the materials presented here. All materials used will, of course, be fully credited."so maybe he can give you contact to Juris Grinbergs - I supose this man should have drawings.
That is all I can do

(hope, you already find drawings somewhere).
