Bobbins.
I make my bobbins with two sizes of thin wall hobby tubing, coat hanger wire and large plastic beads.  I cut the smaller tube to length.  Cut two pieced of wire to length, put them in a vice and bend to shape.  I cut about a 1 in. length of the larger hobby tubing (about 7/32 in or 1/4 in. depending on the size of your coat hanger wire) and put it in the vice.  I stick the smaller tubing in and mash the larger tubing flat against it.  then I insert the two coat hanger wires on each side and (keeping everything lined up) press the whole thing in the vice until it's tight.  I insert some toothpicks in the gaps between the outer tube and the wire as shims.  When they're tight I cut off the excess and  put a little super glue on them.   I ream out the end of the small tube so it won't catch the thread.  Then I put a "lip" of super glue around the opening and place it in the vice with the tube pointing  down, like a "Y."  Super glue is very hard and will dry around the edge of the lip, cushioning the thread.  I drill out the beads, fit them over the ends of the wire and super glue in place.  Building one will cost you more in materials then buying an inexpensive bobbin,  but once you have the materials, you can build all you want.

Bodkin.
A Bodkin is easily made by sticking a needle in a piece of dowel.  The problems are how to stick the back end of a needle into the dowel, how to center it and how to hold it in place once it's centered.    If you have a hand drill and a vice you can put the needle horizontally POINT OUT in the vice, the dowel in the drill chuck and place the other end against the needle.  Take a slow turn and look at the dowel.  If it's off center, you'll be able to see it easily.  Don't worry about getting EXACTLY centered.  Most dowels have grain in the exact center.  Once you've got the dowel centered drill like you normally would.  After you've got the dowel drilled about 1/4 to 1/2 in. deep back the dowel off the needle.  Take the needle out of the vice and snap off the eye.  Now put the needle back in the vice, POINT IN and place the end of the needle into the hole you drilled.  a few turns of the drill will seat the needle where you want it.  Take the tool out of both the vice and drill chuck and put a drop of super glue on the end that holds the needle.   Let it dry and you're ready to go.

Dubbing Twister.
My dubbing twister is make of a piece of 80 lb. stainless steel fishing leader, doubled over, bent to shape and put in an aluminum handle.  I shim with toothpicks and use super glue to hold it together.

Hackle pliers.
You can make hackle pliers out of a length of coat hanger wire, a broom stick handle, a pair of pliers and a file..   Cut about 9 to 11 in. of coat hanger wire,  wrap it once or twice around the brook stick handle so that both ends are pointing in the same direction. Bend the two ends toward each other so that the overlap about 1 in.  Next bend the ends so they're parallel.  Bend them over each other.  Trim the two ends to the same length.  Put a small file between the ends and file them flat.   Adjust the tension and you're ready to go.

Half-Hitch tool.
You can make a half hitch tool out of the barrel of a ball point pin.  I made mine out of a 2 1/2x1/4 in piece of hobby plastic tubing.  I stuck a small piece of aluminum in one end and sanded the other end down.  I made sure the aluminum that sticks out of the one end is smooth and won't catch the thread.   I use either end, depending on the size hook.

Punches.
The white Spider calls for a round foam body.  You can punch out the foam with an empty pistol casing.  a .45 works well for #10, while a . 357 works just as well for a #12.   If you don't have access to spent pistol casings, you can use thin wall hobby copper tubing, available at most hobby shops.  Cut about 1 1/2 in long and wrap one end with masking tape for padding. (let the tape lap over the edge and then turn it into the center of the tube.)
 Which ever one you use, sharpen the cutting edge with a 1/2 in countersink.
take any burr off the outside with a little sandpaper.

I have yet to make my own scissors.  I'm not saying you couldn't make them if you like (I have thought about it.)  It just seems like much more trouble then it's worth.  Who knows?  Maybe someday I will.

I hope this page gives you some ideas about tools you can make for yourself.