I think you might be overstepping here.
I think you might need to read and understand the leading caselaw (e.g., Micro Star v. Formgen, Lewis Galoob Toys, Inc. v. Nintendo of America, etc.). I have done so (for USA jurisdictions); I'm pretty sure you have not.
...tainted by the design of the original...
See, "design" would have to be a patent encumbrance, if at all. Copyrights are abstract properties concerning expressive elements of creative works (in areas of endeavour defined by statute). Patents are abstract properties concerning (useful) ideas and methods.
Designs per se are not eligible for copyright, which is why typefaces ("fonts") do not have copyright ownership (though their hinting programs do). Particular expressions of a design, if put into fixed form and judged to have sufficient creative content, do give rise to copyright ownership. See the difference?
(By the way, the legal term is "derivative work", e.g., in 17 U.S.C. 103. This alternate form "derived work" appears to have recently caught on primarily among open source free-software people, I notice.)
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