In before the naysayers jump all over it screaming "NOT RIGID, WILL NEVER WORK, HOW U EXPECT 2 HOG ADAMANTIUM WIF DAT?"
Looks like someone's having fun, which is important.
Any 3 axis machine, regardless of how lightweight it performs, gives you hands on experience with the whole subtractive manufacturing, CAM, g-code etc which is super valuable.
Making the inevitable mistakes of plowing tooling into the machine (we all dunnit) are going to be a lot less painful and less expensive on a machine like this.
And a super lightweight frame? If you ever go up to a bigger machine, you can convert this to carry a little diode laser (2 - 5W) when you're ready for engraving purposes. Nothing lost!
Grand stuff, keep us posted on progress.