Here a simple to make wind flag with vane and tail can use a blade for speed or ball. Simple to make with simple tools and glue.
Materials;
3/8" X1/2" aluminum tubing 4" length. Upper or outer bearing
1/4" X 3/8" aluminum tubing 6" length inner or lower bearing
. 2 3/8 flat magnets for holding doors closed bearings
JB weld
1/4" round aluminum stock 12"-18" long vane shaft
.030 aluminum flashing vane
daisy wheel or light plastic ball
Tools
hacksaw 32 tpi blade
Fine 8" Mill file
1/4" drill bit
drill motor, drill press or lathe any will work.
chamfering tool
To get the frictionless bearing magnets need to be alighned pole to pole ( north / north or south / south) this repels and the vane floats on air
The inner and outer tube need to fit with little to no friction. Best is to drill out upper tube .010-.020 down 3 1/2" from top and 3/8" from bottom with chamfer leaving a 1/8" wide ring at the bottom.
Steps.
Drill down the upper / outer tube 3 1/2" deep Or polish it only needs to be opened up .010-.015 a drill is fine. Or the inner tubes top end can be polished downto create the same clearance then with the chamfer bevel the lower edge of the upper tube so 1/8" ring is left.
Thru the upper tube drill a 1/4" hole 90* to the tube just inside surface. this is for the vane shaft.
Cut a disc from the flashing to fill each tube. and push in.
Align magnets and mark poles with a marker on face.
cut and form vanes from flashing to desired shape Around 8" wide and 10" long. Lay out center and form a 1/4' radius in it on center line to improve glue bond
glue magnets one on top of the lower/inner tube and the upper in right up to the vane shaft. Make sure the marks are together. and glue vane to shaft.
Let cure
Assemble inner to outer tubes
mount in a vise or clamp a dowel up square. set the bearing assemble on here.
Slide vane shaft thru and the daisy wheel or ball on end where desired find balance point of shaft in the upper bearing tube, When well balanced a very light breath will cause it to rotate.
Glue ball or mount daisy wheel on end. If using the daisy wheel paint one vane black so speed can be seen.
A length of 1/4" round stock can be used to set at the range.
This makes a very sensitive accurate wind vane. A length of large dia fluffy yarn can be added to the vanes lower tail to also show wind speed and very light gusts but in rain may not be useful. In heavier winds the yarn may blow straight and not show a lot. 1 is good but 2-4 are better. over 100 yds.