There are two .scad file, one with simple sharp corners, and one using include <Round-Anything/polyround.scad>// from  [https://github.com/Irev-Dev/Round-Anything](https://github.com/Irev-Dev/Round-Anything)  to round the corners and MCAD to provide teardrop holes and other options. 

I wanted a simple V-block to mount a laser pointer on a surface, and it works well:

You can use a rubber band or a Velcro strap though  the holes to mount the block to a surface, or to mount a shaft into the vee.  If you wanted it more secure, you could use velcro, zip-times, wire, or actual hardware.

This is a 120deg, 40mm v-block with large square holes through each axis:  

You can see some bridging issues under the right-back-top Vee, but it is functional enough for my needs.  

I like printing them on end, so the axis of the V is perpendicular to the FDM layers, and the layer perimeters are strong and accurate.