I have made some metal detectors, both VLF and PI. Until now, one of my favorite is the Minipulse Plus Beach as known as MPP Beach. It is a Pulse Induction detector specially designed to work in the beaches but you can tune it to use in many other situations, like finding Gold nuggets. If you are interested in the project, please check the Geotech Forums, in my opinio, the best forum about metal detectors: https://www.geotech1.com/forums/forum/projects/minipulse-plus/14902-mpp-beach-rev-e Below, are 2 videos I have testing the detector I've build, firt, with a Spider web coil and latelly with a simple mono coil with 3m shield tape. https://youtube.com/shorts/ksGzeMP_x0I?si=OkjFHkC09U5LKZKO The best result was found using the mono loop coil shielded with the 3M tape. If you have already made this detector, please share in the comments your results with it!
There are several ways of storing rocks and minerals specimens. Some prefer to have them visible, other prefer to have them secured in boxes. Personally, I prefer to have them stored in a box, so they don't get dirty with dust, so I decided to build a simple wooden box. It is a simple rectangular box with small boxes inside like drawers that are pulled from top. Dimensions of the main box are 40cm length x 20cm wide x 25cm height. There is space for about 4 drawers inside. I have organized the smaller specimens into paper boxes, although the larger specimens are loose. You can see a small video of how it works to open and pull the inner drawers: https://www.youtube.com/shorts/LhDBVJ7s5Vk I have used this style of box to store minerals but I can be used for any other kind of collectible.