Carlos      (at 4:16am, Thu 18th May, 23)

Hi, Michael!

Yes, they are very useful. And they can be found here in an Austrian platform called "Willhaben", kind of a regional "mini-eBay".
There are just two rules to be observed: 1°- don´t screw them too tight together, because they can later be damaged when being separated (it happened to the lower one in the photo) and 2°- don´t over-strech them, which is unnecessary if they are cleverly combined (it is better to avoid slipping using idler pulleys). The pulleys of "Matador", being made of wood, are of course rougher and offer more friction but, nevertheless, I´ve also obtained good results using them with Meccano models in the past, even being driven by a #22a. You can see what Matador is in my drawer "Alternative building system".

Michael Walker      (at 10:09pm, Wed 17th May, 23)

This looks to be a most interesting method of obtaining different lengths of drive belt.