How can I get an exact match of these two wet molded pieces?

[LMullins]

Hey Folks I'm having a lot of trouble over here.. I've wet molded two sheathes and I just can't get them to line up correctly. I've taken them to the belt sander to try and line them up but I can't for the life of me get it right. 
 

I'd usually get wing dividers and run them along the side of the project for an accurate line but this object is round and there's no hard edge to follow.. and I don't want to leave scratch marks along the inside surface. 
 

what can I do here? Here is the project I'm working on

[DieselTech]

I guess I don't fully understand the question.

Are you just trying to get both sides even for a stitch line?

Or are you trying to get 2 seperate pieces to be joined together lined up to sew? 

Or are you just trying to sand the project edges to make them even, all the way around the perimeter of your project?

Thanks.

[LMullins]

I am trying to get both sides even for a stitchline.

The two wet-formed faces are for different projects. I'm attempting symmetry, but can't quite get them figured out.

I'm looking to get even edges so I can come in with wing dividers lined up to the edge to get equal distance around the wet form. 
 

hope this makes some kind of sense, thank you 

[toxo]

40 minutes ago, LMullins said:

I am trying to get both sides even for a stitchline.

The two wet-formed faces are for different projects. I'm attempting symmetry, but can't quite get them figured out.

I'm looking to get even edges so I can come in with wing dividers lined up to the edge to get equal distance around the wet form. 
 

hope this makes some kind of sense, thank you 

Use a straight edge, sew, cut off surplus. 

[GatoGordo]

Join the two pieces together with rubber cement or double sided tape. Then sand or cut the edges to the size and shape you want. While glued together, the edges will be more rigid and easier to shape. Finally, separate the two pieces. At this point, the two pieces will be mirror images. Finally, mark the stitch line with dividers.

[Dwight]

I sometimes have the same "problem" with pancake holsters.

I learned a long time ago . . . use enough leather so there is at least a quarter to 3/8 inch "extra" all the way around . . . and if it is a larger handgun . . . I'll go for 1/2 to 3/4 inch waste all the way around.

I wet mold both pieces . . . let em dry . . . lay the handgun in the back side . . . apply contact cement around the edges . . . to within 1/8 of an inch of the gun . . . then take the front side . . . lay the handgun in it . . . and apply contact cement to it.  Let the cement dry . . . (you can force dry with a heat gun) . . . put the halves together with the handgun inside the holster.

I use a small Harbor freight belt sander tro even up the edges . . . with a little wooden jig to space it out wherever I want it.

Picture below shows it.

May God bless,

Dwight