You can make boxes, but not electronics? Maybe the 604 is for you ...

https://www.stereophile.com/content/great-plains-audio-altec-604

The old time Altec 604 recreation. Coaxial, high efficiency (100dB!) , crossover already available. Just build a 9 cubic foot box! 
Of course, replace those caps with something good before installing. :)

Best,
E