Lean Pipe is a system that has existed for several decades in some form or another, primarily in factories and businesses through southeast Asia. It was developed out of the "lean manufacturing" philosophy that became popular through the second half of the 20th century.
Its purpose is to give users the ability to quickly build a workstation or other piece of equipment that suits their specific needs, then quickly re-assemble it when needs change. It is designed to provide as much load-bearing strength as possible while also keeping adaptability.
(Please see "comparing building methods" at the bottom of this page for more information.)
Below is a list of common equipment building materials, from most common/least expensive to most professional and expensive, explaining their pros and cons versus using lean pipe.
Pros: Inexpensive, commonly available
Cons: Requires a lot of finishing work, not durable
Pros: Inexpensive, water-resistant
Cons: Weak, cheap-looking
Galvanized or black pipe:
Pros: Strong, commonly found
Cons: Difficult to cut and thread, not many options for attachments, very heavy
Pros: Resistant to corrosion, unique attractive look
Cons: Very expensive, not able to support much weight
Pros: Inexpensive, easy to cut
Cons: Mostly unprotected from corrosion, not many fittings, not designed to support weight
Railing pipe systems (Kee Klamp):
Can support a lot of weight, but very very expensive. Unfinished industrial appearance. Mostly used for safety railings.
Extruded t-slot aluminum (80/20):
Used mostly for technical applications, this is a highly precise yet extremely expensive system.
Square steel frames with a huge number of connectors, this method is also fairly expensive, it's not great for furniture but good for unique or unusual structures or devices
A tinier version of extruded aluminum - good if you want to make a CNC router, 3d printer, or something like that, not good for larger structures.
All prices are in USD.