I had an idea about a phonetic sign language many years ago which would enable whole syllables to be signed in one go, using one hand to sign an opening consonant or cluster, the other for a closing consonant or cluster, and using head/face/eyes/mouth shape/orientation to sign the vowel/diphthong. I now have a better idea in which two syllables can be signed at once, making it twice as fast and I'm looking for feedback, ideally from existing users of sign who could help develop this due to their greater experience in what actually works reliably.

Imagine a 3x3 grid of locations to place one hand, somewhere ahead of your shoulder. The top three "boxes" would represent the vowels e, ay and ee. The bottom three boxes hold the sounds aw, oh and oo. The middle three boxes are for ah, uugh/i, and a (as in "cat" ). The sounds in "earth", "sit" and the mutter vowel don't lead to overlaps in meaning in English, so having them share the central box shouldn't cause any difficulties. The sound u in "up" is just a short ah, or a short oo in some dialects, so you just sign it as one or other of those. (A 3x4 box could be used for languages that need more, and they needn't all use the signs in identical ways, just as different languages vary in their usage of standard alphabets like the Roman one.) The grid of boxes for the left hand would be the mirror image of the one for the right hand.

Initial consonants/clusters would be signed by hand shape. Closing consonants/clusters would be signed by rotation or by direction of movement in the up/down/sideways plane, with straight and curved trajectories like with writing shorthand. Entire two-syllable words like "shorthand" could be signed in one go, making it a fast means of communication, and reading it would be more akin to to reading text than normal sign language.

For the hand shapes, I'm thinking along the lines of using a raised index finger for p/t/k, raised index and middle fingers (and touching each other) for b/d/g, and all four fingers raised (and together) for m/n/ng, with them being pointed up wards for the t/d/n group, tilted outwards to the side for p/b/m (so that's to the right for the right hand and to the left for the left hand), and tilted inwards to the side for k/g/ng. A greater tilt inwards to nearly horizontal and would provide f/v and just past horizontal for th/dh (or you can use horizontal for both sets whenever you don't need to distinguish between them), while h and ch (loch) would be done outwards (and h would be horizontal if you don't use ch). The sounds s/z, sh/zh, l and r would be pointed downwards at different angles, the s/z pair being near th/dh, but sloping down more steeply, sh/zh would point down outwards instead of inwards, and both l and r would point straight down, with l using one finger and r using three (which allows for hl and hr to be signed using two or four fingers in languages that need those, while languages that want to distinguish between m and hm or n and hn can use three fingers for the ones without the h instead of the usual four). Two fingers in a V shape might be used for y, and all four open for w. For hy, index and little finger are raised, and a Vulcan V can be hw, though you can manage without them both, just as many speakers do.

For consonant clusters, a lot of combinations could be fairly regular. The extended finger(s) for the first consonant could be curved to represent a following l and folded right over for a following r. The thumb could be extended for an initial s, thereby enabling sc, scr, scl, st, str, sp, spr spl, sn, sm, sl and sy without any complications. I'm not setting any of this in stone at this point - it's important to change it if that improves clarity or ease of use. Not considered yet: tw, dw, cw, cy, gw, tsh, dzh, (plus important foreign ones such as pf, shp, sht, shc, shn, kn, shtsh which should ideally be covered too). It won't matter much if some of these have to be done in more random ways.

The set of closing consonant clusters is different from the openers, and it can't be covered by hand shape, so we must use movement and orientation instead. The hand can be rotated to different angles (quite in addition to the direction of point), and can be static or actively rotating too. This could be used to signal closing clusters beginning with r, those ending in s/z, and for both of those at once - we have two directions of rotation for this and two angles that don't obscure the number of raised fingers (one of which would be the standard angle used for open consonants. We also have movement in the up/down/sideways plane and with straight and curved paths which can be used for single consonants and for all other clusters, perhaps by adding a terminal flick. We also have speed of travel and distance travelled, which can distinguish between different consonant types (the pftsc-type group, the bvdzg-type group and the m-n-ng group), while the direction of movement would be the same as the direction of point for the same sound as an opening consonant: t moves straight upwards, for example. Most sounds have already been covered just in the course of writing this, which I hadn't intended, but remember that none of it is set in stone. The patterns of these sign elements are related to the patterns of sounds themselves, and that makes it easier to learn them as their distribution is substantially logical, and I want to maintain that logic. We also need to cover: rc, rg, rt, rd, rs, rz, rsh, rl, rth, rf, rv, rn, rp, rb, rm; x, gz, ts, dz, ps, bz; ft, ... there may be more, but it's late at night here, so I'll just post this now and hopefully I'll be able to go on editing it for a few days before it locks (I think there's a time limit on editing things). If it locks before it's finished, I can just put new versions in the comments, and I can always start a new thread with a definitive version at the top of it later when it's all complete.