Computer with just an FPGA

A computer just running on an FPGA - and it will be transparent.

Jet Again: basically a rotating shell where the turbine wheel is "welded" to the shell

... basically a rotating shell where the turbine wheel is "welded" to the shell.

A balsa humanoid should be affordable and easy to construct

3d printed screw compressor with ferrofluid sealing (inexpensive and efficient)

3d printed screw compressor with ferrofluid sealing (inexpensive and efficient)

Plasma doubble Z-pinch jet engine

One plasma pinch compresses air and the other fuel vapor through the middle. If it is good enough for fusion it is good enough for jet engines. 

Giant 3d Printer Based on Excavator

3D printing buildings

The Nordin Jet Engine

The Nordin Jet Engine as a jet turbine with a single moving part. The whole jet revolves around an axis including the shell.  Fuel is either fed through the axis and through a centrifugal pump or "inhaled" by the jet from the front in the form of gases.

Advantages:

1. Easy to manufacture (even 3d print)
2. Low friction and long life
3. 100% tight between blades and casing
4. strong (since turbine blades and casing form a single object)

Other variant: fuel acts as diffusor: