Build a house for mason bees

What can we use instead of bamboo tubes or a power drill if those are hard to find?

Use clean paper drinking straws or rolled cardboard tubes cut to 10–15 cm and keep a closed back by retaining a natural node or plugging with a small piece of wood, and if you don't have a power drill use a long nail or awl with adult help to make 6–8 mm holes.

What should we do if the drilled holes split the wood or the bamboo tubes wobble when inserted?

If holes split or tubes wobble, reclamp and drill slowly with a sharp 6–8 mm bit, sand the edges, then pack each tube with a thin paper shim or a dab of waterproof glue and secure the bundle tightly with strong tape as in the step that pushes tubes into holes or bundles them.

How can we adapt the project for younger children or make it more challenging for older kids?

For preschoolers have them mark hole centers, sand entrance edges, and decorate the roof while an adult handles cutting and drilling, and for older kids have them measure and cut 10–15 cm bamboo, drill straight 6–8 mm deep holes, and build a removable inspection panel to check sealed nesting tubes.

What are some ways to extend or personalize the mason bee house after it's finished?

Personalize and extend the project by adding a labeled weekly observation chart to record sealed nesting tubes, planting pollinator flowers nearby, installing a slightly tilted waterproof roof as described to keep rain out, and sharing photos and findings on DIY.org.