One of the great aspects of ARCHICAD is the simplicity of developing new & custom library parts. But sometimes, in fact most times, close enough is good enough. Before spending time to develop new custom objects, ask yourself, ‘do I need this specific object, or is an out of the box library part close enough?’
What we need in a library part:
-A library part needs to contain the correct and accurate information, first and foremost. Now with ARCHICAD’s Properties and Classifications, we have all the information management we need for all elements, so no scripted parameters are necessary.
-A library part needs to be the correct size. The overall dimensions and clearances need to be included in any library part, and almost all AC Library parts include parametric size and clearance parameters.
-A library part needs to be located properly. Hotspots can be scripted for easy placement, but for the most part, ARCHICAD objects include all the necessary hotspots for placement and adjustment.
-Lastly, a library part should be as close to the specified manufacturer’s model as possible for documents and visualization. This is the lowest priority.
I routinely build custom objects for clients. Sometimes, I am able to provide a recommendation for an object already available. Some times, requests require a specific manufacturer or detailed model for appliances, furniture, plumbing fixtures, etc. As an example, I have recently been asked to model a specific bath tub; a custom concrete tub, generally oval with a slight taper to the outside faces. There is a very close approximation already available in the ARCHICAD Library:

The out of the box tub is so close to what the consultant proposed, it hardly made sense to make anything custom. But the interior designer wanted a rendering with their exact design, so a custom tub was built. The out of the box object met all but the last requirement listed above; that is, precise visualization.

In this case, the client needed to see the 23º slope to the outside of the tub, so a custom object was made. In most cases however, plumbing fixtures can be a close approximation, or even a completely different object, just set to the correct size and located correctly. Most of us have done this all the time with appliances. You rarely need to see the exact refrigerator, or range, or dishwasher. The AC Library parts are generally good enough. But if the client is trying to decide if Wolf or Viking is the correct decision, and they are willing to pay for the services, why not make the custom object?