I just downloaded this and got an error which I discovered was due to trying to save to the wrong directory.I would make sure to direct it to save the project to the packages folder in the Mods folder inside the Sims 3 folder instead of to screenshots which will cause an error message to pop up.
My new guest cottage blueprint shows up in another Sims 3 folder when I copied the package to that folder in build mode.

Under LIMITATIONS the author said:
"The blueprint tool works on a single room (as the engine defines it). This means an area that is completely surrounded by walls OR halfwalls. If you have halfwalls between a living area and kitchen, that should be fine, since you'll have an opening for the sim to walk through."

This mod is like the best thing that has happened in my life! I have already saved lots and lots of all kinds of blueprints and use them constantly I love to build a lot, but not to spend an eternity on furnishing every single building, 'cause I'd rather make entire towns and worlds, so this mod is essential!

I've made a whole house blueprint with gaps in walls for doors and copied it as a blueprint costing 250$ in game fully furnished.

Thanks! I only wish I'd found this mod sooner! This will save me so much trouble in designing!

::nab:: --think I`ll give this a try.

Thanks a ton for this! I like EA's blueprints, but it's nice to be able to make your own!

I'm using a quarter round tile pattern for my bathrooms. It's one tile that has to be rotated with '<' or '>' to complete the full 2x2 circle. When I place the template, they all have the same orientation. When I try to use the eyedropper to clone the tile and replace the floor, it says "Nothing here can be cloned". Any idea how to fix this? I don't mind the doors being moved so much. They are easy to fix. But these complicated flooring patterns is one of the prime reasons for using templates.

p.s. I think I'm going to love this once I get used to it I've found a style I like for my overstuffed house, but my sims can't afford it all at once. When I made templates for the bedrooms, I forgot to select the category, so till I replace them, they are misc rooms.

This is p h e n o m e n a l. It's my new favorite thing, I can't believe I only saw this now! Thank you!

This mod is amazing! I just used it in 2020 and it still works! So happy to finally share room builds in Sims 3!

It takes some trial and error but still works in 2022.

The fail message "The given key was not present in the dictionary" means it can't create the file because of user error, like instead of 4 Walls you have 3 Walls and a Fence.

If I upload a house that I made using the blueprint maker, does the room/blueprint appear in the list of those who will download it?

For people who have gotten exceptions that prevent saving, I think I've figured it out: it's a problem with the screenshot for the room.

A room kept throwing exceptions for me and refused to save, until I tried a larger picture of the room. If you've edited the picture to crop it, make sure that the picture isn't really small. 610x842 kept throwing errors and I couldn't save. Changing nothing in the room at all, but using a new picture that's 1009x731 did save without any errors.