Those ghost hunting shows and alien hunting shows keep showing something called a RemPod. I was curious and researched it to see what's inside.
Someone took one apart online and inside was an electronics kit from a company called MatLab. I found the kit in Amazon and ordered one along with an antenna. Here is a housing that holds the kit and antenna. The top is printed in clear PLA and the lower half is black. Three very small screws hold the two halves together. Four kit LEDs shine through the top and a little Piezo unit chirps away. The pc board is around 51x51mm square and the antenna has a 7mm diameter. I added a maintained push button in a 16mm hole to turn it off. Here's the kit: https://www.amazon.com/dp/B01MRCPHN5?ref=ppx_yo2ov_dt_b_fed_asin_title And the antenna: https://www.amazon.com/dp/B0C89GMBM5?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1