I have two built and tested Eggtimer Classic Altimeters and an Eggfinder LCD-GPS module kit for sale on eBay for those of you that are interested.
https://www.ebay.com.au/itm/Eggtimer-Classic-Altimeter/133606705515https://www.ebay.com.au/itm/Eggfinder-LCD-GPS-Module-Kit/133614872559
https://www.ebay.com.au/itm/Eggtimer-Classic-Altimeter/133606705515https://www.ebay.com.au/itm/Eggfinder-LCD-GPS-Module-Kit/133614872559