That's the most logical thing i've read relating to SCP 682, i understand it's hard to do, they even tried using the model from SCP Six Eight Two, but it came up to difficult to manage and glitchy. but from what i read, it's humanoid in nature, it dosen't have too look like a lizard with a large body, standing straight is usually it's normal form, how do you think they get it around to other SCP's for testing, the room SCP 173 is in is pretty small, and just for him, the termination test that SCP 632 went through with SCP 173 took hours in that small room, what stopped it from changing size and escaping. I'm sorry if i got you mad with wanting a model but a swinging arm in the end of the game isn't so amazing.
EDIT: I just read the description of SCP 131, they seem like little eye drops with one eyeball and a wheel underneath them, SCP containment breach lets you pick up items, including useful and useless SCP's, they would be a item pick up, when ever 173 is around, they could just stare at it until you leave then call them back, there's a record of them doing this within there Addendum. A nice little buddy to make things less scary for all of us for those like me, that jump at anything.
EDIT2: Yes, type in SCP-054, to call in the Water Nymph
MOD EDIT: Merged triple posts.