When using Thingiverse, scroll down and look below the items image for a field marked "files".
If the number of files is greater than 5, we will not be able to complete your request.
When using MakerWorld, look to the right of the item's image for a clock icon followed by a time, designating how long a print will take.
Anything in excess of 3 hours will not be able to be completed.
Single files that contain multiple parts in excess of five pieces will not be able to be completed.