No experience with anything tools that can cut off a finger or worse! I admire those who can create and refurbish instruments. That said, have you checked the Congaplace forum? They have some info about DIY cajons.
Greetings to all the brother. In Cuba when I was growing up they were playing Guaguanco in the house were I was born every Sunday, and they were using, beer/ cases, furniture shelves, etc, which I started using too, until I started playing drum set and playing real tumbadoras, after that. Gerry Zaragemca
Sela Cajons have recently released the CaSela Professional Snare Cajon. Which is a professional quality cajon which is screwed together quickly and easily. This makes for a pro sounding drum at a lower price.
Throughout the history of the existence of cajons and things like them, they have been a very basic box. Even with the explosion in popularity most cajons are still not much more sophisticated than something you can build with a table saw and a Saturday afternoon. It seems only logical that innovation, craftsmanship and artistry should be applied to the cajon to make it a more versatile instrument. Somewhere there is a mad scientist of cajon making who is trying to put as many noises as they can into one box. I don’t wanna get too precious here but I am a drummer/woodworker who builds cajons that combine fine woodworking with a sensitivity and versatility several steps beyond the cajons you know. Please check out the youtube channel mediumsizedog and let me know what you think. If this sounds like a commercial pitch not appropriate for this forum category I’m sorry and please let me know. Thanks, Medium Size Dog.