I'm unable to write a critique due to lack of premium status (so please refrain from bringing this up - I'm unable to purchase it), but I will breifly state what I think of the plushies.
Overall, a great effort worth commending. The seams between the sections of material appear to be professionally stitched and blend together well.
The one flaw I noticed was the positioning and size of the metroids' fangs. In no stage of their evolutionary cycle do metroids possess fangs located on the outer 'corners' of their membranous bodies. Instead, two large and inward-curving fangs are positioned beneath the metroid's body and are centred, between them existing two smaller and also inward-curving fangs. I am aware of the fact that having created the plushies in this way would mean that they could not properly be supported upright due to the presence of the centred fangs, however this is the correct anatomical structure of (most) metroids.
Nevertheless, they still look amazing and I would most definately purchase one (or perhaps a second one for a close friend) if I had access to some method of payment. Alas, I do not.
Nice work, once again.