NextPCB offers two free PCBA prototypes for Raspberry Pi RP2350 or RP2040 designs, sells RP2040 for 30 cents during mass ...

No user-serviceable parts inside? Give me a break! The head unit is tough to get to, but the PCBs within the chassis use ...

After all, for most products, the delicate electronic components on that PCB are tucked safely inside ... such as the enforcement of design partitionings — such as keeping analog circuits ...

Fortunately, there is e.g. a free KiCad library with ready-to-use PCB antenna designs to help one get started with a custom design, as well as many other resources, covered in the article.