The bi-fold door is made from pressed hardboard in a mould, with an "egg box" packing in the middle (made from cardboard) with very (cheap white wood) lippings around the edges. Yes it is flimsy and lightweight, and you can get better quality ones for more money. For an alcove or cupboard, these are usually fine. Where's the handle? For the boxing-in of the boiler, never gonna be perfect but I would have a) tried to make the small side flush with the boiler. (if possible) b) fixed 2 vertical battens inside the box where it touches the wall and fixed 4 screws with screw cups to hold it in position, so it doesn't flop about. You need to gain access to service the boiler. c) would have cut a u shaped hole for the cable to go through, where the side panel touches the wall, so the cable is horizontal (looks ugly if the cable is at an angle. d) Tried to make the top of the small side panel higher to hide the gap. The screw heads can be filled and painted, so not a problem. If the wood he's used is MDF it should have been MR MDF (Moisture Resistant) and painted both sides and edges (I use oil based varnish on the inside to stop moisture absorption) then sealed with a silicone bead on the worktop to stop water creeping up the MDF swelling it up and rotting it. MR MDF is NOT waterproof. Ordinary MDF, even if painted, will "suck" in moisture from the air in kitchens and bathrooms, that's why you should always use MR MDF in those places. On the whole, the carp hasn't done a bad job, but didn't put much thought into it.