Alex explained that his early prototype of the go-kart involved welding the frame, but he quickly learned that welding isn't a good option. Welding is strong and a great option if you have the resources and knowledge, but if you don't it is intimidating and can be expensive. Like most DIYers he thought there has to be a better way and set out to find it.
At first he found conduit fence connectors and gave them a try, but learned that they wouldn't work either because he had to heavily modify them.That proved to be just as difficult as welding so he started searching again.
He stumbled across Maker Pipe specifically the T Connector. He was excited to learn that they work with 3/4" EMT conduit which meant he didn't have to weld or modify the connectors except to add an extra bolt for added strength when necessary. To finish off the frame he added black shrink wrap that not only looks great but also holds up to rocks and debris.
You can find drill batteries in almost every home in America, but you usually won't find them strapped to a go-kart. Alex decided against a combustible engine because he didn't want his young kids to refuel with gasoline. Drill batteries are a safe alternative because they are easy to charge and have built in safety measures that prevent over heating etc. Battery life depends on the riders weight and what size the batteries are. In this case Alex's son is able to get roughly 40 minutes of ride time.
Alex built this go-kart with safety for the rider in mind. He reinforced the frame with bolts through the connectors where needed. He added a mechanical brake in case the electronic brake failed. There is also a kill switch to shut down the kart in case of an emergency, and of course a seat belt bolted to the frame.
*Alex did a great job with safety, but remember to build within your limits and ride safely.