Plugin should be needs only if you want some "parametric" setup. If you want to create just static object, internal command edge to spline is enough.
For example.
1, Create cube 100*100*100
2, Add cloner (grid mode, 3*3*3 with size 100*100*100)
result is 27 cubes perfectly lay each other and "share" the same edges
3, rightclick on Cloner/ Current State to Object
4, middleclick on newly created cloner null object
5, rightclick / Connect Objects and Delete
with first step you convert parametric cloner into separate geometries, with second you´ll select all newly created geometries and with last step you make just single polygonal object which contain also "inner" cage (all edges from single cubes are still there)
6, select newly created single object, rightclick / Optimize
7, switch to edge mode, select all edges, rightclick / edge to spline
8, drag out spline from child position of geometry object
9, hide everything instead of spline to see nice spline cage in viewport
In these steps you optimize mesh, select all edges (Ctrl+A in viewport in edge mode) and create spline cage
10, Add connect object as parent of spline cage
11, Add FFD deformer as child of spline cage (use fit to parent command to adjust FFD size exactly to spline cage size)
12, In point mode with selected FFD deformer select all FFD deformer points and deselect all 8 corner points only
13, Scale them to your needs.
Connect object make sure/optimize spline cage as whole, not all spline segments separated. FFD cover/influence whole spline cage and with selected control points and scale deform spline cage as you wish.
you could see deformed spline cage is "linear". Select spline cage object in Object manager and change intermediate points from Adaptive to Uniform. (You could also adjust number of intermediate points if deformed cage is not as smooth as you want)
timespace.c4d