Tar heel's nests can be washed and reused several times. This is worth thinking about when you consider the price. If you already have many of the materials lying around the house making one might be less expensive but if you have to buy it all from scratch it really won't be unless you need to make like 5 or more nests.
DIY isn't always cheaper. But then my DIY nests was a cause of much suffering... and I could have bought one for much much less.
I do agree with Skw's comments about them being too deep and not having big enough outworlds. This is the main reason they aren my favorite nests. For that I'd say foranto or underground citi. And when it comes to what I use the most? Underground citi.
How can making them be more expensive? I don't know what the type 3 material is but lets say i use grout or plaster....
I can buy the mixing powder for 6€.
Plastic dishes and tubes maybe 2-3€
Arcylic bought in large panels of 1m2 are the most expensive part...They cost me like 10€ but i can use it for several nests...
So the grand total is under 20€, but for a single medium sized nest is probably less because of the panel...
For me buying lets say a fortress type 3 would cosy me like 120€ whit shipping 😶
Definitely not cheaper for me at least lol, they may not turn out as pretty the first few times but I'm sure whit practice they will functionally similar.