With the nozzle on the sealant use the caulk gun to squeeze it along the edges of the perspex where they join. This will be messy so put protective sheets down and wear old clothes. Smooth the sealant using a piece of card. Make sure all the space between the sheets is filled and the sealant is smooth.
Rest the final piece of perspex on top of this square. You might need to put something inside the box to keep it in place. Use the silicone to secure this into place in the same way as you did with the sides.
Leave overnight or until dry then peel off the protective plastic sheet. Gently scrape off any excess sealant using the blunt edge of the perspex cutter. Be careful not to scratch the box though!
Now just find the perfect spot and give your air plant a home.
If you’re looking for planter DIY tutorials then check out my most popular ones right here!
*This post contains affiliate links.