From the project chat:

https://hackaday.io/messages/room/283874

Alex Camilo writes:

• instead of running the display through a cutout i think it's better to have the connector on the top.
• this way we can use an acrylic spacer and have all the components on the top of the bottom board.

• the acrylic spacer would be a 5mm (or 9mm) donut.
• we would use m2 threaded SMT standoffs soldered to the bottom pcb

https://www.digikey.com/product-detail/en/w-rth-elektronik/9774015243R/732-7069-1-ND/5320674

• the top PCB would be passive, with silk screened artwork on the top.
• the bottom would have components on one side.

There are two ways to do the straps:

the way the openHAK does it with a notch in the PCB outline covered by resistors

https://www.hackster.io/news/openhak-is-a-completely-open-source-fitness-tracker-launching-on-kickstarter-5c9cfda3e2bb

HACKSTER.IO

OpenHAK Is a Completely Open Source Fitness Tracker Launching on Kickstarter

A large portion of you are probably wearing a fitness tracker right now as you read this. They're a great way to collect data on your physical activity and ensure that you're getting regular exercise. But while basic fitness trackers are very affordable, you're almost always stuck with proprietary hardware and software.

Read this on Hackster.io

Alex Camilo9:41 PM

for a good look 

or, we just do a notch like this

https://www.cnx-software.com/wp-content/uploads/2016/03/ESP8266_Smartwatch_Large.jpg

CNX-SOFTWARE

• benefits of notch: single side load.

• then we get a strap like this and it covers the bottom (eBay link)

• the one with the resistors looks nicer but complicates things.

this decision won't affect layout too much so ill make it at the end when everything else is done. I am leaning toward notches.

Michael Welling writes:

• I think the straps are more cost effective
• it will also protect the skin from the PCB