A simple candler can be made from a maglite torch. The important thing is not to let light escape at the edges so the shell lights up and obscures the inside detail. A light proof seal gives a very good result.
The box is a strong top from a malt whisky box, the polstyrene pad grips the torch firmly, and is made from 3 or 4 layers of thiner poly sheet so it's easy to cut the hole neatly. The foam rubber pad spaces the egg off and cushions it and the light seal is inner tube rubber with a 25mm hole through it (don't make the hole too big). The edge of the hole has lots of 3mm long cuts in it (made with sharp nail sissors, my swiss army knife came in handy here) to form a fringe which is highly flexible and seals the light. The black tape is strong duct/ carpet cloth tape.
HF