It's really amazing about your works, i can see all of the details you've been sculpting. Congratulation about your works.
About the 12'' tall figure, i think it can be made in clay mold, and made into fiber glass mold or plaster mold. The cost will be much lower. According to this size, a lot of sculptors will follow this way. Unless it contains a lot of details which can't be sculpting by hand, but it also can be fixed at fiber glass mold.
The 3D printing is too expensive, we've got an sculptor which need to print an 10CM high bust, and the expense is more than 1000USD.
And the 28'' tall figure, i suggest you can make it into clay mold, and there is other oil clay maybe better than the ordinary clay.
We are an foundry. You can see some of the sculpture works by our website at www.chinaartcasting.com