One of the many benefits that 3D printing technology offers is the ability to print hollow parts. While it is upto the customer to decide if the 3d printed part needs to be hollow or not, we may suggest hollowing of the parts as one of the ways to reduce the printing costs
. Other than the project budget, it is also the end-use application of the printed part that needs to be considered while deciding to hollow out the parts. While objects that require high structural strength would require it to be solid from within, maybe even to the fullest extent, objects which do not require a high strength can be hollowed out, keeping only the surface walls with some suitable thickness. This will reduce your printing costs to a huge extent.
The other consideration would be the printing technology utilized by us
to print the 3D models. While FDM technology has the capability to print only the surface / shell of your object (while also controlling the amount (density) of material that goes inside the object) at the time of printing, other technologies such as SLA, DLP, SLS, Binder Jetting would not let you print a hollow part, if the part has not been hollowed out during the modeling phase. For these kinds of printing technologies, to print a hollow part, it is necessary to hollow out the 3D model during the modeling process itself, while also adding escape holes at suitable places in the 3D model for the trapped resin / powder to flow out of the printed part.