Vertical bars: create a single horizontal 1D bitmap (pref. hold-and-modify); set BLPxMOD to negative the number of bytes of a single row (so the same row of pixels repeats over and over again) and animate the 1D bitmap - there's a nice demo that does this under the pre-tense of an undocumented instruction (the joke being there's no need for an undocumented instruction)
endless blob: to draw endless BOBs, allocate as many framebuffers as memory will reasonably allow and flip through them, drawing a BOB on each framebuffer with some sine path motion as it is about to be displayed, net effect is the BOBs keep on coming and flowing perpetually like millions.
Glenz vectors: use blitter to draw lines & blit into bitplanes with polygon filling mode, you'd need at least three bitplanes, one for the silhouette of the shape, one for the front-facing faces and one for the back-facing faces, then set up the palette so it's "just right" for the combination of planes to give a semi-transparent effect.
A site that goes into old school amiga demo techniques would be awesome! Would love to read up about even basic stuff like dot record breaking techniques & bitmap rotation and zooming techniques (eg. Brian the Lion intro screen comes to mind, as do the rotating platforms in Turrican 3)
I wonder if there is a site that explains copper bars, vertical bars, endless blob, glenz vectors etc.? Would be interesting to read about that again.