Voxel graphics is ok time-wise.
All the assets (except for te sky) for my NeonHead for example were made in Goxel and it in sum (even with 3d font) it was somewhat about a day of work. For 9-day jam voxels are quite affordable i think.
Have a look (downloadable has better graphics then web cause GLES3). https://houkime.itch.io/neonhead
Also there is openSCAD which let's you literally write 3D models as a constructed solid geometry. If you write a nice set of your own functions it can look very neat and consume quite little time. It can also be wrapped in Python via solidPython for a better syntax.
Now if i wanted to do sth complex which can't be done with Goxel easily i would definitelty go for openSCAD. Especially for models of tech and such. You can look at one of my MIT openscad models here, it has a file and a png preview https://gitlab.com/Houkime/little_flyer