I would advise to use heatshrink and also to glue the cells together. Some people don't, but your packs will stay in much better condition if you do (especially in a XX4 worlds edition).
1. Put the heatshrink on and shrink it.
2. Line cells up +-+-+- on a flat surface and align them with something straight with something heavy at either end (no offset is required with 3000s) then superglue or shoegoo them together, or to make it easier, get the battery jig.
3. Tin the bars and cells wire and plug
4. Attach the bars with a really powerful soldering Iron (60W is good but 100W is even better
(the Deans jig comes in handy again here)
5. The Deans plugs are available in bulk female packs, so you shouldn't have to buy too many spare male plugs
6. If you want to use less wire, you can cut Ultra Deans in half, but with use, you can lose some of the tension that holds the connectors together so well, plus it's a lot of work, so be warned.
7. make sure you follow the Deans Instructions and have the two halves connected when soldering the plug