You aren’t limited to the built-in Sample Spaces. To make your own space, create a plain text file containing a list of 4×4 matrices generating the space’s group of covering transformations. See, for example, the built-in files for
Curved Spaces uses the (row vector)(matrix) convention rather than the (matrix)(column vector) convention, so the matrices may be the transposes of what you were expecting. In the spherical case this makes no difference because the transpose equals the inverse, but in the flat and hyperbolic cases it’s important to get it right.
Let your text editor save your 4×4 matrices as a plain .txt file, then manually change the filename extension to .gen. To open your file, put it in the Sample Spaces folder and choose Space ▸ Change Space… from within Curved Spaces.
Macintosh: To reach the Sample Spaces folder, right-click the Curved Spaces icon and choose Show Package Contents, then go to Contents/Resources/Sample Spaces.
Curved Spaces 3.0 includes a smaller, more streamlined library than Curved Spaces 1.0 had. The omitted spaces are available upon request.