There are a number of producers of custom LEGO compatible pieces, how would one add such a custom piece to the LDD software, or otherwise make use of them?
In the comments you wrote:
...For the record, I am willing to consider answers that address other software as well. But I currently only have the LDD, so am completely unfamiliar to any other software out there. – nijineko
Brinklink offers two programs that could be right up your alley: