Graham from Lazy Cyclist had this simple way to make a headset press.  I can see Park Tools wincing at the mere sight of it, but it beats what I used to do to my headsets with a 2×4 and hammer…
Get more pics and instructions on his post.  Quite simply, you use a really long threaded rod, washers and bolts…and two wrenches to tighten the bolts with.
While the old threaded rod press works (I’ve done it at least 20 times myself), it’s immensely more time consuming than the proper tool. It’s a real pain to keep the headset cups plumb as they are being pressed into the frame and takes allot of trial and error to get the headset in. There is also significant potential to damage a frame if you force a cup in crooked with a threaded rod system like the one described.
I agree , the right tool of course is a campy seatpost ,
I have a version of this and it is a little tricky during setup but if You want to make it more simple lock 2 nuts together on the top or bottom of the rod and use a ratchet it drive … it it will compress much more “liniear-aly” and will not ofset (as much) as say an ajustable wrench or box end
