In wanting to keep more than just Honey Bees, and Mason Bees. I found myself wanting to help the Bumble Bees as well. So I used some cheap Terracotta pots I had laying around.
Step 1: Drilling the Goal
I used a 5/8" ceramic tile hole saw to drill in the first hole in the upper side of the Terracotta pot. This would be the entrance to the nest. I took a smaller saucer and drilled 3 holes in it. Those 3 holes come in handy for giving you something to hold on to when placing that in the bottom of the larger flower pot. Also those 3 holes are for water drainage, and air flow. So that gets place in the bottom. I then used some old burlap for inside the nest. I just cut it up for the nesting material.
Step 2: Cad & Spacers
I didn't want to drill out any more holes then I had to. I needed some vents in the top though. So I designed 3 little spacers that will hold the lip or top 1/4" higher than the larger flower pot rim. Those were printed on my 3D printer. I used a much larger saucer that fit perfectly on top upside down for a lip.
Step 3: Location, Location, Location
At this point the last thing to do is to find a location for it to go. I dug about 2" 1/2" into the ground and placed it in there. Put the dirt back up around it, and now it sets. I put some honey on the inside hoping to use that as bait for a Queen Bumble Bee. If that works that would be great. If not, them next year I will buy a Queen and colony. Thank you for checking my project out. I really appreciate it.