Greenhouse - a topic that also came up with us. We have decided against it so far.
Even though I would like to have some early tender radishes and possibly some homegrown cucumbers, for ME the effort and benefit in this matter are in too extreme a ratio. If at all, we might still get a cold frame. Next year, however, we will first try our luck with a polytunnel. Maybe for a completely different reason, I will change my mind about the greenhouse. In the first year, when we created our bed, only very few snails found their way to us. This year, this has already "increased a hundredfold." If the trend continues, one might have to think about a physical barrier (greenhouse). Well - next year I will first indulge in the tedious hobby of a "small gardener" – snail hunting.
Greenhouse self-built: I still remember my father's "do it yourself" greenhouse (when he still had his garden). He cobbled it together himself in the early 80s during GDR times. The base consisted of 3 - 5 rows of bricks (probably on a concrete foundation). The greenhouse itself was assembled from various old windows that my old man got from all over the place. The roof as well – but with the possibility to lift the windows. Later he devised a hydraulic window lifter (typical engineer). The fluid in the piston expanded at certain temperatures, and the plunger lifted the window (no idea if I used the right terms). Although the greenhouse did not look nice, it served its purpose (like almost everything you cobbled together yourself in GDR times). Early radishes and salads in early spring, later the "cucumber production" began. A few tomato plants also inhabited the greenhouse (I think). When the family groaned because of the mass of cucumbers, Dad just took them to work. His colleagues gladly bought the "overproduction" from him. When around the turn of the millennium he gave up his garden, which had meanwhile turned into a water plot, the greenhouse was still standing. ([Wassergrundstück] - after the reunification, several industries that took water from the little river flowing near the garden area closed down, the river rose, causing the groundwater to rise and almost all gardens in the area to flood. Perfect conditions for rice cultivation. :confused)