The tools used can be simple hand tools or larger, electric shop tools. I'll go through what I used and how I made mine and you can adapt to your situation.
A dry birdhouse or bottle gourd
A long, thin stick, like a dowel
Heavy wire or coat hanger
6" x 6" block of 3/4" wood
Hot melt glue
Felt (for base padding)
Hot melt glue gun
Stain, varnish, etc. (optional)
Rasp or sandpaper
Ruler and pencil
Step 1: The Gourd
Be forewarned that birdhouse gourds are prolific viners and will spread rapidly across the ground and climb about anything that they encounter. See my Instructable on growing squash vertically. https://www.instructables.com/id/Grow-Squash-Vertically/
Harvest the gourds by snipping the stem with a pruner Make the cut a couple of inches back up the vine from the gourd. Do this prior to a frost and store them in a cool, airy place until they have lost most of their weight and the shells are light brown and hard. Some dark mold spots will have formed on the hard shell but don't worry. These will come off when you give the outside of your gourd a good cleaning. Don't worry about the inside yet.
Indeepknit has a good instructable on cleaning the outside of your gourd. https://www.instructables.com/id/How-to-clean-a-hardshell-gourd/
Step 2: Prepping the Gourd Vase and Base
Use the thin stick to stir around inside the gourd to loosen the dried membranes and seeds. You may need to use a piece of heavy wire with a hook at one end to remove some chunks. Dump these, saving some seeds for next year or for gifting to gardener friends.
Stain, varnish, or paint the gourd however you want. There are lots of suggestions on-line but I left mine plain. Avoid putting wax etc. in the center of the bottom where the glue will go.
Cut a base to about 6" x 6" from whatever wood you want to use. Remove rough edges and sand the rest smooth. Stain, varnish or finish the wood however you want. Avoid putting wax etc. in the center of the top where the glue will go.
Cut four small (1" x 1") squares of felt and affix them near the corners of the bottom of the block using a dot of hot-met glue. Sign and date the bottom.
Step 3: Finish and Fill
Now just arrange a variety of dried grasses, weeds, flowers (real or imitation) in your natural vase. Don't put any water inside the gourd for fresh flowers.
The gourd top and stem can be used as a rustic table place marker or note holder.
Birdhouses: If you decide to make a bird house from gourds, I suggest using a hole saw to make the entrance hole. No perch is needed for wrens.