Ok, let me show you the parts we need. You will need the PCB, of course, the HC06 Bluetooth module in the SMD version, the small OLED display of 0.46", a small LiPo battery of 100mAh and for the charging circuit, you can take all the components ouf of a TP4056 module. The ICs, the resistos and capacitors and even the USB connector could be used from a module if you don't want to buy all the components separately. Then, for the ATmega328 module, you could take it out from an Arduino NANO clone, in that way you make sure it works and t has a bootloader. Make sure the Arduino clonse is using a QFN package for the ATMega chip. In the same way, you could also desolder the CH340 IC from the back and solder it to you PCB. Together with these components you will need my design of the case so downlaod it and print it out with PLA material. You will also nee some sort of mirror and a plastic fresnell lens. You can buy those for cheap from the internet. All links are below in the part list. So, this is all we need. I've took the small ressitors, the capacitors and the 16Mhz crystal from the Arduino clone. If you want, you can buy all those separately from the links below.