At the top of the picture, there is the chassis containing the buttons, to the right there is the connector for the 9V plug that goes to 7805, screwed to the chassis and leaned on a button.
Always on the right but at the bottom of the chassis, there is the USB socket, secured with two-component glue, where I plug the cable that leads to the USB input of the effect. At the center there is Arduino (below) and the USB Host (above), all spaced from a plastic base, using 2 screws, also fixed with two-component glue.
On the left of the photo is the HC-05 and the switch that serves to disable bluetooth when I have to program Arduino.