What spindle would you recommend for machining and profiling parts with small slot drills in thin brass and non ferrous materials?

The ER16 or standard Taig lathe headstock have a number of toolholders available, Taig or Peatol in the UK sell blank toolholders which can be easily adapted for use as toolholders for endmills, or arbours for slitting saws etc.

There is the Kress spindles which offer higher speed but lack flexibility in terms of workholding, machining toolholders etc.

For light duty engraving there's also the Proxxon IB/E engravers, good for small precision drilling in PCBs etc.