There are many different putty’s out there, feels like a jungle. Someone said that Squadron green putty will shrink after 6 month making you very sorry that you used it on your nice styrene model. And there are white and red putty. Please tell me what putty you use for styrene and why? I want a putty that dries fast, is easy to sand and give me a nice finish. And will not shrink after a couple of month and destroy my model. 
Model airplane modellers use typewriter correction fluid. White-Out is one brand. Works pretty good and is easy to use.
EL, in N. America the autobody repair industry uses a compound called “Bondo”. It is a putty used to fill dents and holes in automobile bodywork. It is a good product, doesn’t shrink, and is sandable. I have never used it, certainly not on a model, but it could be useful for your purposes. There are also plumber’s putties that one uses to seal around the flanges of drains in bathroom and kitchen sinks, for example. I don’t know how it sands, if at all, but it can be smoothed while wet and that may be all you need.
Two possibilities for you.
-Crandell
I’ve used vinyl spackle in the past. It fills in gaps and can be sanded easily. If the gap is deep or wide, I usually try to apply it in several thinner coats; sanding in between coats, if necessary.
Tom
I’ve used Squadron Green several times in the past without any shrinkage.
The only specific use I remember was an Albatros DIII (WWI airplane) which had a crudely molded fuselage section. The putty worked out great, it was a nice model, one of my favorites, but it got damaged while moving one time and has since departed.
Just don’t put the putty on in thick layers and give it enough time to properly cure and you should be fine.
I’ve tried to use Squadron green putty, but the stuff is so dried out and thick that it can barely be squeezed from the tube. I don’t know if that’s its normal consistency, but it’s very difficult to smooth out when it’s so dry.
If it has started to dry out, it is very difficult to work.
I store mine in a sealed ziplock bag, since the tubes tend to develop cracks which let in air and dry out the putty prematurely.
Also, I would stay away from the epoxies (such as the JB Weld pictured in the OP) for general modelling uses, it’s too hard to work for fine detail. It’s great at what it does, though.
Squadron putty that is dry as it comes out of the tube is old, I usualy throw it away by then anyways the new tube should come out wet and spread smooth, also i’ve never had the putty shrink months later.
Out of all the putties pictured, I think you may be satisfied with the Milliput. Here is the description from Micro Mark:
Milliput sounds great. But there are 5 different grades. What grade is ok to use with Evergreen styrene? http://www.milliput.com/home.htm I have Evergreens styrene how-to book. They recommend Nitro-stan 9001. Is that a good putty?
I use “Acryl-Blue Glazing Putty” by 3M. It comes in a 21 oz. tube and will most likely last me forever. I got it at a shop that sells auto body supplies, paint in particular. I’ve used it on several projects, and it’s worked beautifully. I’ve also got an earlier tube of stuff that I can’t find–I think that one’s Dupont.
It does shrink if you put it on thickly, but after it’s TOTALLY dried, you can just put on more–no big deal. If you paint over this stuff before it is TOTALLY dried, you may be sad at a later date. The thicker the layer, the longer the dry time. Sometimes I can sand in half an hour; sometimes I have to wait a day or two. Think “patience”.
I believe the stuff called “bondo” is used for doing the fill-up for body dents. The stuff I use is designed to fill little holes and bubbles in the bondo.
Conveniently, the 3M stuff is a pale blue color, so it shows up on white plastic nicely.
Why do I use it? Cause it works, it’s cheap (compared to teeny-tubes), and it is color-tinted. The Dupont one was grey–OK on white–not so good on grey. Dupont may make theirs in color, too, now. I bought that tube maybe 20 years ago.
Ed
I’ve used Squadron Green and Testors and hated them. Went back to Bondo auto putty. Works great. Sands smooth and EZ and doesn’t shrink. (made to be on a car exposed to extreme eliments.)
It’s 10 times cheaper and available everywhere.
Works well for filling in wood benchwork gaps too. I was thinking about trying it for roads too.
Have you tried the Apoxie yet? I like it, one nice thing is that it can be smoothed with water and a paint brush, or a little spit on your finger.
Tom
DO NOT use "Plumber’s Putty, it contains oil that will ruin your subsequent paint/decal work.
I use Bondo. Almost exclusively. It is easy to use, inexpensive, and (at least over here) readily available. It doesn’t shrink that I’ve ever seen and I’ve been using it for quite a few years. Back in my aircraft modeling days, I used Squadron Green stuff. Never had a problem with “shrinkage” (as George Kostanza might say). -George