This simple DIY project uses 9V battery and synchronous step-down regulator to generate the required voltage.
The main assembly consist of several 3D printed parts, a pcb assembly, a switch button and other parts which are listed in AssemblyBOM.pdf. All electronics components you need for the pcb is described here BOMforPCB.pdf.
The PCB design was created with Altium Designer 19. All mechanical parts and assemblies were created with SolidWorks 2020.