Do you have any soldering experience? You need a soldering iron, solder, solder flux will help alot
i would suggest not soldering unless its just a show truck. solder tends to be very weak and will not hold up under a lot of pressure. i messed around with trying this a while back with a few dif types of solder and tubing. nothing i tried was nearly up to par with the durability you NEED for crawling. keep in mind the chassis you can buy off crawler sites are built for proformance. they are strong and give a ton of articulation while keeping low GOGs.