my bitch has 3 pups (was 5 but 2 were stillborn) so the remaining healthy 3 are just over 4wks old now!! they are all doing great.... except one who is very timid and shy. when we get the pups out of the box he tends to lay down and not really join in with the other 2 who walk around and investigate and play with mum.... occasionally he will go behind my partners feet (~who will be sitting on the sofa~) and just stay there and hide. when i get him out for a cuddle he seams quite calm but after 5 minuets or so shakes and crys until i put him back into the box... the other two pups are not like this, one of them is very friendly and playful... the other one is quite playful and enjoys being cuddled and such..... but just that one doesnt seam to like much except for being in the box.
what can i do before this becomes a problem? or is it normal in toys at this young age?

4 weeks it too young to expect toy pups to have much confidence outside their whelping confines.

Mine,who I can pretty much guarantee will be outgoing at 6-7 weeks, are often shaky and reluctant at 4.
I don't push them at that age, I let them enjoy their security and comfort zone til they're ready.

I don't breed Toys but agree, too early to do anything, give him a little longer, you're taking him out of the security of his whelping box and he is obviously very uncomfortable with this, and sounds as though he is frightened, perhaps he is just not as mentally developed as his siblings, may be normal as development for each pup can be different, or there could be a problem perhaps a lack of oxygen at birth, all will become clear as he ages.  If he is still the same at 8 weeks might be worth a check over at the vets, you do get different characters in litters some can be the 'quiet' ones :-) as Toys are generally with the breeder for 12 weeks you have plenty of time, so don't worry yet, as long as he is eating well, sleeping, toileting and showing no signs of discomfort just wait and see........

In the meantime,  I've always allowed all pup to come and go from their 'den' as they like, those first loan steps help to build confidence, can the box be adjusted so they can now come out on their own into a safe sectioned off area to wander and explore? Along with socialising with yourselves? Might help the little one build his confidence and independence. But, for now, if he doesn't wish to come out leave him be............ I'm sure he will begin to explore when ready. :-)

I've had the breed for years.  I think your lack of experience is showing here.  You are really pushing far too soon.  Have you discussed with your mentor what she would advise?

>when we get the pups out of the box

You shouldn't be getting them out.  They should be left to choose.  If your "box" isn't one that the pups can choose, I would advise that you alter your setup.  You are frightening the pup if he "shakes and cries." 

One of the reasons I won't have people round with a litter this young.  I know I would be pretty disparaging when they "just want a cuddle."  :-)

I have pups of mine that have passed their PAT dog tests, so I must be doing something right. 

I think small toy pups are so different to larger breed pups that they are almost like different species. Toys are more like kittens. They are SO much slower to do everything! Hence needing to stay at least 4 weeks longer than other breeds.

A good friend of mine comes to visit regularly and hence she has seen a few litters of my toys grow up and develop, and indeed she has 3 that I have bred. This year she got to see a litter of my large breed be born, and has then visited around once a week, as she wanted to follow their development. She was absolutely gobsmacked at how different these larger pups are. In her words at about 4 weeks "They are like proper DOGS already, not like puppies!"

Goldmali has given a perfect example here.  Well explained Marianne.

Quite agree with my medium size primitive hunting Spitz breed pups want to be romping outside at 4 1/2 weeks maximum, and would be screaming the place down if confined too long. 

By 6 weeks their 6 x 10 foot playpen and shelter is too confining and they have the run of the dogs area, and only want to come indoors for brief periods and to sleep at night.

I confine them indoors to a puppy pen though, as with my poor sight, clumsiness and several canine oldies, I could not personally cope with pups lose underfoot.

I like visitors right from the start if they want to, but pups are pretty interactive by 3 weeks, but most interesting from 4 weeks.