We present a novel paradigm to assemble complex miniaturized free-space optical systems.

It combines contact-less femtosecond laser-activated alignment with femtosecond laser three-dimensional manufacturing of a single substrate incorporating optomechanical elements.

As a specific demonstration, we showcase a palm-size, GHz repetition rate femtosecond laser cavity almost entirely made of glass, whose alignment and lasing operation is permanently tuned and achieved contact-less via laser-matter interaction using another femtosecond laser.

The manufactured Yb:KYW oscillator shows self-starting mode-locking above 300 mW of incident pump power and a maximum slope efficiency of 30%.

The oscillator delivers  a clean diffraction limited beam, with < 200 fs Fourier-transform limited pulses and near kiloWatt peak power.

Over 1 hour, without active stabilization and open to the ambient air, the average power fluctuates within 0.34 % RMS standard deviation, on top of a 2% linear drift.

From the radio-frequency comb, we extracted a pulse repetition rate of 1.0925 GHz, deviating only by 860 kHz from the value expected by design, and the signal-to-noise ratio reaches as high as 76 dB.

With an emission centered near 1 micron, it is well suited as a seed laser for GHz burst machining, as a light source for nonlinear microscopy or as a frequency comb.