Use a barely damp microfibre cloth on the acrylic and the screen, and isopropyl alcohol on the circuit board only. Alcohol clouds the acrylic permanently, and water sits on the board instead of evaporating, so it is worth keeping the two apart.
The acrylic casing
Do not use alcohol, glass cleaner or any household solvent on the acrylic. They cause crazing, a reaction in which the plastic develops thousands of tiny internal cracks and turns cloudy. It cannot be reversed.
Use a microfibre cloth, the kind sold for spectacles, slightly dampened with plain water, and wipe gently.
The circuit board
Flux residue from soldering, and general dirt on the board, come off with isopropyl alcohol (IPA). Water does not belong here.
Dip a cotton bud or a soft brush in the IPA and work over the area gently. It dissolves the residue and evaporates without leaving moisture behind.
Keep the IPA off the acrylic and the screen while you do it, and let the board dry completely before you power the device up.
The screen
A dry microfibre cloth is usually enough. For a stubborn smudge, put a single drop of water on the cloth rather than on the screen.