Tube / valve amps are quite easy to build. As previously noted, most of the physical work is metalwork. Don't expect your product to look anything like fancy. Expect to lose everything you invested in the build, like zero resale value. The big con of tube amps is the real risk to life, from the HV psu. A review of other post in this forum may suggest that even experts don't have exactly the same opinion, as to what is 'safe' and what is 'unsafe'. Neither absolutely exists.
Fail points in amps are usually the tube, easy (not always cheap) to replace. Next something in the HV area, from transformer to a blown resistor or bank of electrolytic capacitors. Add in modern 'improvements' like SWR protection (assumes you get too excited to look at the meter), on PCB boards, adds another area of possible downtime.
1500 out is in itself a serious thing, assume 3000 in or about 12 amps current draw at 240 very round figures. I would respectfully not start with something that 'big', you will see comments about amps with 20-25KW output, oddly, DX stations rarely hear those commentators on the air. If you really 'must' build a tube amp, I would go for a single 3-500zg, at 600 watts output.
Building or assembling a solid state amplifier is generally more complex as a project (opinion). They are fairly broadband so the design principle is different from tube amps, which must be 'tuned' (matched to the antenna). Much less (but not zero) HV risk, voltages are usually 50v or less. But any failure means either getting out the hefty sobering and/or small soldering irons, and finding out if the output solid state devices are sill available.
