Earlier this year, I built a 20w Marshall Bass & Lead clone over in PNG, in an Ampeg Portaflex type configuration.
I liked it so much, I built one to use in the USA, using a fair bit of leftover bits and bobs:
And because I like the sound with the two channels linked, I skipped a second set of inputs and added a channel selector switch.
Since I don't have a woodshop here, I just went ahead and bought an new Ampeg Portaflex flip top cab with a 15" speaker:
Figures if I'm copying their concept, may as well give them some money.