Introducing the K’Nex Building Sets – Things to consider before buying (2024)

In this article I want to give you an overview of the K’nex building sets and discuss some of the pros and cons. I will also take a look at some of the basic sets available and what age children they would be suitable for.

The K’Nex building sets are very different from building blocks like Lego and you can’t build solid walls with them. They consist mainly of a variety of plastic rods and connectors with a few other pieces like wheels and gears. These can be connected in many different ways to allow many different models to be built.

They have 2 ranges of building sets: one targeted at the consumer (that’s us) and one targeted for schools – the education range.

In addition to this there are 3 different size ranges: the K’Nex classic that I will be discussing here, the K’Nex micro that has pieces about half the size of the classics and the Kid K’Nex with larger pieces designed for small kids. The 3 different sizes do not work together, so keep an eye out for this when you are shopping.

The fact that these sets are used in the classroom already says a lot about their potential for helping children learn and develop important skills. The one area where they are used a lot is for teaching technology and engineering skills with sets such as the Real Bridge Building set. The education range covers all the STEM (Science, Technology, Engineering and Mathematics) areas of learning. I will discuss these in a separate article, but I wanted to show you that these building kits have many educational benefits. This is a good reason to encourage children to play with these types of toys.

The sets are meant to encourage open-ended creativity where children get to use their imagination to build their own creations and play with them. The model instructions included in the sets are meant to give examples of what can be built. Children can then modify these models and begin to develop their own designs.

The pieces are all color-coded. This makes it easier to find pieces that are the same and also to follow the pictorial instructions included in the set.

Let’s take a look at the basic (classic) sets in more detail.

To avoid repeating myself and telling you the same thing repeatedly for each set, I want to summarise some of the aspects that apply to all of the sets.

The manufacturer’s recommended age:

All of these sets have a suggested age range of 7 to 15 years. Feedback from customers on Amazon indicated that a 7 year old child struggled with these sets, but from 10 years up this was not a problem. The younger children needed help with figuring out how to connect the pieces and also with following the instructions. The older children coped a lot better.

The included instructions

Many people were disappointed with the instructions. They are not truly step by step instructions and take jumps from one stage of the creation to another, especially with the bigger models. Many of the younger children were frustrated by this and needed help to be able to build the models. It is easy to miss something and make a mistake and not so easy to spot the mistake until you are quite a bit further along with building it. The color-coding of the pieces is supposed to make it easier to follow along.

Now for some specifics of the basic sets

K’Nex 375 Piece Deluxe Building Set

• Number of pieces: 375 classic pieces, including wheels
• Suggested Age: 7 – 15 (see notes above)
• Building ideas included: 30
• Storage tub: yes
• Price range: From $12.93 to $19.99
• Amazon average customer rating: 4.6 / 5

This is one of the smaller sets and is useful for building small models. For children that want to build large models they will find that they don’t have enough pieces, especially of the longer connectors. A good variety of models can be built, including a crane, a helicopter and a truck.

What people liked about this set:

• The instructions include moving, interactive models.
• The pieces are easy to snap together.
• It kept the children busy for hours.
• Encourages children to use their imagination.
• The models are quite durable if they are put together properly and can be played with once built.
• A set that can grow with the child as they build more complex models.
• The plastic storage tub is good to keep the pieces in and big enough to add pieces from more sets.

What people did not like:

• There are no instructions for some models shown on the box.
• Larger models have a picture only and no step by step instructions.
• Not enough pieces to build some of the larger models.
• Instructions don’t give much detail for larger models. Just a picture and you have to figure out how to build it.
• It is difficult for younger children and children with low fine motor skills to put the pieces together properly.

Overall this is a good beginner set if you don’t expect too much from it.

K’Nex Classics 50 Model Building Kit

• Number of pieces: 700 classic pieces, including wheels
• Suggested Age: 7 – 15 (see notes above on the appropriate age)
• Building ideas included: 50
• Storage tub: Chest-shaped cardboard box
• Price range: From $58.95 to $64.41
• Amazon average customer rating: 4.6 / 5

This set has more pieces, allowing larger models to be built. The building ideas include instructions for sea creatures, a hot air balloon and a sand castle.

The customer reviews on Amazon were mostly positive about this set.

What people liked:

• A good variety of models can be built with the set, including taller structures such as windmills and buildings.
• The box is quite big and can store incomplete models together with the pieces and instructions, keeping them out of the way until later.

There were very few complaints, here’s a summary of them:

• There are no gears and other interesting items that would enable more building options.
• Not enough building ideas included in the set (more can be downloaded).
• One customer complained about the rods not being rigid enough to be able to build tall structures. I did not see any other complaints about this so I am not sure what to make of it.

Nobody mentioned the problem with the manufacturer recommending this from age 7 upwards, but I think the same applies as for the other sets.

This set offers good scope in the models that can be built and is definitely a step up from the 375 piece set.

K’Nex 521 Piece Building Set

• Number of pieces: 521 pieces, a mixture of classic and micro K’Nex
• Suggested Age: 7 – 15 (see notes above on the appropriate age)
• Building ideas included: 35
• Storage tub: yes
• Price range: From $18.98 to $24.99
• Amazon average customer rating: 4.1 / 5

This set had quite a lot of complaints about it, although a few customers were satisfied with their purchase.

What people did not like:

• There is nothing on the packaging that tells you that both classic and micro pieces are included. Remember that these do not work together so this like getting 2 small sets, one of each size. This was an unpleasant surprise for most customers.
• The storage tub is large and the pieces fit into the bottom 2 inches of the tub. They complained that it took up too much space for what it contained.

What people did like:

• The storage tub is big enough to add pieces from other sets or to store small models.

I don’t like the idea that includes a mixture of incompatible pieces (classic and micro), so I will be giving this one a miss.

K’Nex 70 Model Building Kit

• Number of pieces: 705 classic pieces
• Suggested Age: 7 – 15 (see notes above on the appropriate age)
• Building ideas included: 70
• Storage tub: Chest-shaped cardboard box
• Price range: From $29.75 to $44.99
• Amazon average customer rating: 3.9 / 5

This set includes pieces to build a plane, animals, amusem*nt park rides and trucks. It has almost the same number of pieces as the 50 model set and I am battling to find out exactly what the differences are (except perhaps more building ideas). It offers a good variety of building options and is liked for that reason.

This set had the same complaints as for the 50 model set: it was not suitable for younger children; there were not enough of the long rods and the instructions do not step you through the building.

Again the treasure-chest box is a lot bigger than it needs to be, but has space to add more pieces.

Again this set offers more scope than the 375-piece set and is a lower price than the 50-model set. Looks like a good option.

Which one would I choose?

Having looked at what these sets offer, the customer reviews and the price, I think the 70 model set is the best value for money as a K’Nex starter set. The 50 model set has almost as many pieces, but costs a lot more. It’s just a pity they don’t supply it in one of those nice plastic storage tubs.

Buy the 70-model set now

Do you agree with my choice, or would you choose a different set? I would love to hear your opinion, so please leave a comment below. If you found this article interesting, please share it with your friends.

Perhaps you would like to see a more specialized K’Nex building set – take a look at some of my other reviews like theMini-Golf Building Set, the Exploring Machines Set or the biggest K’nex set of all – the GrandFather Clock.