Short Replacment Rapido Couplers in the New BS&F

In last week’s post I released my designs for short replacement Rapido couplings to reduce the distance between coaches on N Gauge rolling stock.  You can find the post here.  Since my post Shapeways have announced their new pricing structure which will be rolled out on the 7th of October.  For the most part the changes are an improvement because several materials will be come cheaper to print in. However, due to a complication with the Short Rapido Couplings model, it will become impractical to print the model as it is.  In this post I will share with you what changes I am making to continue to supply these couplings.

The default material for these parts is Shapeways Black Strong & Flexible.  It is one if the cheaper materials, ideal for parts like this which have a lower level of detail but which still need to be functional.  The new pricing structure for BS&F will now charge a fee for each part in the model, consequently with a pack of 20 couplings this makes the model impractical.

To solve this I have added all the parts onto a sprue, as shown below in the rendering.  The sprue has been drawn to the minimum requirements so as not to waste material or increase cost, and to make it easier to remove the couplings from the sprue.

Short Rapido Replacments Tree Black

The couplings are also available in the Frosted Detail material which is not affected by the new pricing structure.  However, as the model needs to be updated to incorporate the sprue this means the FD price will also be slightly affected. Both kits for 20 and 40 couplings have now been updated ready for the change on the 7th and are still available on the Shapeways site.

My original intention for the couplings was to have a 3D printed product which was delivered ready to use.  And I can still offer that service by order these couplings in bulk myself and offering them for sale from this blog/website.

I can do this by ordering several hundred couplings at once; then it becomes practical to draw things in a different way as Shapeways software is very clever in how it calculates volumes and printability of models.  For example, if I draw two rings, as shown below, interlinked so they cannot be separated, just like a chain, the software will recognize that this is actually one part even though the rings do not touch each other.

3D Rings

By using this advantage I have drawn a cylinder full of holes.  Each hole is not quite large enough for one of my couplings to fall through so once the model is filled with couplings the Shapeways software will only charge for one part.

Rapido Replacments Cylinder

If you would like a pack of 20 or 40, or any other number, of Short Replacement Couplings that are ready to use on delivery I can supply then, please use the contact page or send me an email at

So you can choose either to order the couplings attached to the sprue direct from Shapeways with their delivery schedule, or you can purchase direct from me which may have a slightly longer delivery time, unless I have that number in stock.

This change in Shapeways pricing policy also affects a few other models of mine but nothing that requires a change like this.

Next week I really do plan on getting back to the HO Scale Union Pacific water tender project and I hope to be able to share with you some photos of the painted car.