Good Afternoon,
I first want to say that I am an employee with DragonPlate and I am only on these forums to answer questions and offer tips or assistance. I only offer the links below for ideas and do not expect you to choose DragonPlate for your solution.
Typically, a tube for this application would be a roll wrapped twill finish tube. Specifically for your application, a 0.875”ID tube from dragonplate has a 25.4mm OD (
http://www.dragonplate.com/ecart/product.asp?pID=6140&cID=135). With 2kg on each end and being fixed in the center, it would deflect around 1.5” on each side. If you want to less deflection and don’t have constraints on the OD, I would suggest going up in size.
With regards to your connections, we at dragonplate have two different solutions:
The first option is to use our carbon fiber tube ferrules:
http://www.dragonplate.com/ecart/categories.asp?cID=165. One could bond one end into a tube and drill a hole for a push button system. We don’t offer the push buttons because drilling holes in carbon introduces stress concentrations into the epoxy matrix that could cause cracking and breakage. You can use tubes from 0.875”ID (which has the 25mm OD), up to a 1.75”ID tube.
The second option would be our threaded end connectors:
https://dragonplate.com/ecart/categories.asp?cID=308. These are bonded into the ends of the tube and allow the assembly to thread together like a pool cue. The connectors are aluminum and the threads are steel. This assembly would be a bit heavier, but the joints would be more rigid and you would see less deflection. The pullout strength of the epoxy with our proprietary design is higher than the max failure stress of the tubes. We offer these connectors in the tube size you need and the connectors should be flush on the OD.
My last piece of information is about cutting. Tube can be cut with a band saw and a very fine tooth blade, a diamond blade on a saw, or a grinding wheel surface as with a Dremel tool. Be sure to wear eye protection, a tightly fitting face mask, and gloves as the fibers/dust is extremely irritating to the skin.
I hope this information was helpful for you to make a decision on how to move forward. Have fun working on your project!