Duct tape is a stereotype, but having a few kinds of tape including duct, electrical, and athletic can be useful. Less so for building objects like you’ve shown but often for fixing or sealing.
Steel wire is cheap and sometimes comes in handy for providing simple shaped objects or securing pieces together flexibly.
Wooden pallets can often be acquired for free and either used as-is (I have two serving as gardening boxes in my backyard) or stripped down for wood.
Paint! Anything you build can be made 75% less obviously DIY with the appropriate coat of paint applied. Spray paint requires no brushes but does require careful choice of workspace to not make a mess. Canned paint needs only a work surface with a layer of newspaper laid down, but requires some hygiene to maintain brushes and not let it dry out prematurely.
Duct tape is a stereotype, but having a few kinds of tape including duct, electrical, and athletic can be useful. Less so for building objects like you’ve shown but often for fixing or sealing.
Steel wire is cheap and sometimes comes in handy for providing simple shaped objects or securing pieces together flexibly.
Wooden pallets can often be acquired for free and either used as-is (I have two serving as gardening boxes in my backyard) or stripped down for wood.
Paint! Anything you build can be made 75% less obviously DIY with the appropriate coat of paint applied. Spray paint requires no brushes but does require careful choice of workspace to not make a mess. Canned paint needs only a work surface with a layer of newspaper laid down, but requires some hygiene to maintain brushes and not let it dry out prematurely.