Failure of measurements

As it turns out, trying to design plumbing pipe furniture using measurements is futile for someone with borderline OCD, like me.  I measure pipes and add them together, but they do not piece together at that measurement.  I try to use Photoshop with the grid turned on, but the errors are even more noticeable.  I am going to have to simply use my best approximations, which I never like doing.  After all, I can always loosen one joint a partial turn to get everything the same length.

I always welcome your constructive criticism.  Click on the Comment link below next to the icon of a pencil; it may say "No" or have a number in front of it.