Yes, it is true.  It is possible to build your own homebuilt jet aircraft.  But, it will take a lot of commitment and dedication, as well as time and patience.  You can build these models to full scale or smaller.  You will need to have access to the proper materials and tools, and possibly need to salvage parts from airplane bone yards.  However, the challenge involved can come with immense satisfaction of knowing that you designed and built your own jet aircraft.  While there are blueprints and designs to get your started and give you ideas, much of the actual project will be up to your own personal preference.