I used pine for the frame but stained it with a walnut stain to match the dresser. I used spar varnish over the stain to add a nice water resistant layer. This has worked out very well so far.
Being an indoor greenhouse I use mild chemicals for insect control. Neem has been effective as well as insecticidal soap. I usually place the plants in the bathtub for their treatments and allow them to dry before placing them back in their greenhouse.
This greenhouse has brought me great satisfaction over the past two winters as it brightens a tough part of the year for a bonsai enthusiast. I am not trained as a carpenter or an engineer but simply put an idea to paper and figured out how to make it work. I wanted to share this with the bonsai community as a possibility for some who have may have minimal skills like me but would like a way to house a small number of tropicals through northern winters. I don’t have formal blueprints or scale drawings but would be happy to answer any questions concerning construction if someone would like to attempt this project.
Obviously the size of this greenhouse limits the size of the bonsai. One could have a single larger bonsai or numerous shohin or mame bonsai. Most of my tropicals are shohin and not finished bonsai but are in training... BUT isn’t that the point…having something to maintain during the long winters.