I have been continuing with the experimentation with Tiltbrush speedsculpting, using this as the means to jumpstart ideas that I can finish either in 2d or 3d. I leave the symmetry tool on, and then use the matte poly brush for the big shapes, than add more detail, timeboxed at about 15 to 20 minutes.
The export process direct to Photoshop as a 3d object was not working too well for me, mainly because this gave me less control over the lighting of the object as I imagined the airship fitting into my scene. Modo was an easy input and ouput to just modify the lighting quickly, and then make a render along with a mask that Photoshop could use to isolate the ship.
Photoshop does a great job for image filters, layer management, and masking, but personally, I find the painting tools through the brushes to be tool slow from moving my Wacom pen to seeing the resultant stroke, whereas SketchbookPro is much faster on the uptake, and has more 'painterly' brush kits.
In this case, I placed the SketchbookPro .tif file as a linked Smart Object within Photoshop, so that when I made changes to the greyscale SketchbookPro image, it updated automatically in my Photoshop file underneath the color adjustments and sepia filter.