Although Aerospikes are not new, what is different about this is the fact that it has been 3D printed where the builder is able to play around with complex geometries not able to be manufactured using conventional methods.
Click the picture below to see the testing video.
This particular engine has made use of printing for the nozzle geometry and embedded cooling network as stated in this article.
A little off topic but worth posting about, Vector Space, a small satellite launch vehicle provider has recently posted a blog about Aerospike rocket engines.
As stated in the blog post, California State University, Long Beach and Garvey Space Corporation partnered to develop a 1000lbf aerospike and a 1300lbf 10 chamber plug aerospike. I was in Mojave in 2009 and was lucky enough to witness the launch of the P10 vehicle with the multi-chamber aerospike, unfortunately as stated one chamber did not ignite taking out two adjacent chambers, causing the rocket to cartwheel off the launch rail and impact a short distance away. This was the first time I ever saw a liquid fuelled rocket fly, even though it never achieved its purpose on this day, it did not put me off!
Below are a couple of videos about Aerospikes that I found interesting.
Or if you are wanting a greater in depth of the challenges and manufacturing process, the video below is very good.