The LED's should all be joined together with a common anode and 5 separate wires running of each five banks back to a plug to connect to the ignitor board. I used a relatively expensive microphone plug. It looks cool so Im happy with it.
Once all the LED's are constructed and you have a plug on the end, it's time to find something to put them all in. Other sabers I have seen on the web use polycarbonate tubing. I'm on a budget and don't actually expect to be beating anyone with my saber so I opted for the cheaper acrylic.
The tube is water clear so with the LED's in place you can see each one light up which doesn't really give me the saber glow.
So some type of diffuser is required. I am still experimenting but I'm quite happy with clear cellophane that I scotch bright in various directions.
I feed the rolled up cellophane into the tube then feed in the LED's. Some care is required but the LED's are quite flexable in this condition so put up with a bit of abuse.
On the end I bought a plastic bung that fits in tightly so should prevent any moisture getting in.