Homebrewing
My favorite part of the hobby is to built homemade electronics, antennas and other stuff, see some of my projects:
usdx - Proof of concept, TX part need to be finished... TBD… YT link
AVALA TRX - Great QRP SDR IQ transceiver by YU1LM, built in 2016. I built also separate VFO with SI5351 module and Arduino, controlled by PC via USB. See also F5NPV
Autotuner ATU-100 by N7DDC - Great automatic tuner, available as a kit from AliExpress, I can recommend Up Tech Store.
Good regen receiver by PA2OHH