Design
The playsets come with predrilled holes and specific instructions for assembly. This makes it easy to put together, but impossible for it to be reconfigured substantially. There are options to make minor feature changes, but you cannot change the footprint or configuration of the main structure.
Small Add-Ons
Gorilla Playsets does sell several add-on products that can be fitted to existing playsets per the instructions. These include telescopes, steering wheels, handles and safety pads.
Swings
With the swing sets, the hanging swing often can be switched depending on the model. For example, you can hang a punching bag, infant swing or glider swing instead of a standard swing.
Warranty
Reconfiguring any Gorilla Playset against the manufacturer's instructions may void the warranty. The Gorilla Playset warranty states in part, "Defects that develop as a result of faulty or improper installation of the product also are not covered by this warranty.... This warranty does not cover products...which have been modified or repaired by unauthorized persons."