I need a "cheap" software program for designing my Maker Pipe projects. I am using an iMac computer. What design software are people using?

Fusion360 is free for non commercial use. I will tag you on the post containing the step files for our connectors that you can use for designing. Hope this helps. 

I use a free open source CAD program called LibreCAD117. It's not 3D capable, but 2D is fine for me and it creates extremely accurate drawings. I can take my measurements directly off the drawing and get perfect cuts every time.

I am probably the wrong person to ask, but I use SketchUp Pro, which is spendy, but is part of my general woodshop toolkit.

I actually use PowerPoint and do drawings in a 1-inch=1-foot scale. It’s not 100% accurate since you can only go to 2 decimal places on measurements. And you can’t do  3-d models to move around. But it‘s good enough to play with different configurations and ideas. 

I go to a page Setup and make the page a bit bigger than my project, up to about 40 by 40-inches/feet. Draw conduit as rectangles using whatever length x .06 .  3/4” conduit would actually be .0625 wide (1 inch in PowerPoint is 12 inches physically so 1divided by 12 is .0833333 per inch multiplied by .75 (3/4 inch) = .0625 in the drawing = 3/4” physically).