I’ve always been the type to keep my soft swimbaits in their original clamshells but at this point ive got so many keitechs, swammer, and other clamshell swimbaits that it’s taking up too much space. I’m thinking about throwing them all in a 3700 box. I’m wondering if I can mix and match different brands in the same box and separate them with the dividers or if that wouldnt be enough and the different plastics would react to each other. 

Keep Elaztech away from any other plastics.

Keitechs aside, i think you’ll find that the clamshells inside a bag will end up taking up less space overall than moving everything to 3700s unless you're only taking 2-3 of any given color.  I’ve done both now.  I have a 3700 with ‘the basics’.  When i was in the kayak i would always have that box.  Then if I thought it would be a plastics heavy day I would grab my speed bags of bags of plastics.  When that box runs down I won’t refill it.  Speedbags are smaller and hold more.  In the 3700s the colors do bleed among the same brand let alone across brands. 

 

Keitech clamshells take up space and if you use them a lot then a 3600 used for them isn’t a bad idea. 

As long as you separate them with the dividers you should be fine. I use a 3600 thin box for various plastics, but I generally keep the colors separated. 

 

I will even keep zman stuff in there, but that compartment only holds zman from brand new box. Elaztec doesn't like plastisol. 

 

Paddle tails can get kinked though in my experience. 

You can keep softer plastics like Keitechs in boxes without too much distortion, especially if they are stors in your boat.  If they are in backpack or bag that constantly moved, then they get can jumble up a bit and can get bent out of shape slightly.  If you leave them out in the winter or a really cold fall night, the plastic can "set" in the position they are in and be difficult to straighten out.  

With SI Fats you can cut around the baits and have the baits in single shells.  They still take up more room than they would if you removed them, but they are protected from kinking and it saves a lot more room compared to storing them in the whole package.

Elaztech baits are vulnerable to kinking and can be almost impossible to straighten.  Elaztech and other elastomer baits can warp plano boxes over time.