just a little newbie input from me. I am using a DIY dry box also. But i use thirsty hippo. I bought a 10L "airtight" (lock and lock wannabe) box from one of those plasticware wholesaler at $8 (I got mine from the one next to MSC). I will then lay the inner faces with bubble wrappers. I get those big plastic tub of thirsty hippo and open them all up to get the dessicator on the inside. Then i will use a plastic box, underlay with tissue to suck the water, and put in the dessicators. I don put all the dessicator from one tub. I store the rest in a good ziplock bag for future use. I also mount a hygrometer in my dry box (cost about $7-$10 from Homefix, goto car section).
U will have to play around with the amount of dessicator to be placed to get the right RH. Mine worked well and stayed in 40-50% RH, i only need to change the dessicator and tissue about once every month. I open my box about 8-10x a month. My pack of 3 thirsty hippo tubs bought a year ago, and i am still using the dessicators from the first tub.
To be honest, the only reason why i still use a dry box is because i stay in a hostel. Not convi to have a dry cabi around. If u are not limited by circumstances, get a dry cabinet anytime. U can also keep your certificates and other stuff in them. U will not go wrong with it.
Hope this helps.