Use the Customizer tool (click the button above) to create a series of lined-up polygonal through-holes within a solid block. You can define the diameter of each hole, a universal offset value to customize the fit, the spacing between the holes, and the thickness of the object. This is useful for testing and generating perfectly sized holes (for press-fits or whatever else) with your printer, and the resulting object can be a good starting place for more complicated parts.
This is inspired and adapted from nophead's polygonal hole test object and this blog post. In a nutshell, accurate sizing for printed holes depends on two factors. First, the number of polygons should be equal to twice the diameter (in mm) of the hole. Second, the diameter should be adjusted to account for the straight lines making up the polygon. Finally, a global offset value provides a way to increase or decrease the hole sizes overall so you can achieve a desired fit or clearance.