Here's a few suggestions I have for the Workshop, specifically.

• A method to temporarily cut away a section of the model, to more easily access the inside
• An instruction builder, something like Lego Digital Designer or a number of the other 3D modeling programs
• More robust part search. Reference the part number that includes the color to the basic part number already listed. This would be especially useful so that you can search the number in an instruction manual instead of having to go to bricklink, then back to mecabricks. This gets tedious.
• Undo functionality, like CTRL+Z
• It may be beneficial to rework some of the shortcuts to bring them more in line with the shortcuts of major modeling software like Inventor or AutoCAD
• Mirror functionality
• Easy decal/sticker creator, for those bricks that have stickers stuck to them. The bricks that have printed graphics, should indeed be their own brick, but those with stickers should have a way to slap the sticker on and snap to a certain surface of the model.
• In the same token, it would be cool to be able to generate the graphics, brick graphics or stickers, so that someone can print them out and build the model
• Malleable strings/chains/ropes/tubes. It goes without saying, this is a much needed function or else the parts library will be filled with 6-100th generation copies of virtually the same parts. LDD even has it. It would also promote using those elements to make your own designs, and could prove interesting. It should be simple to create 5-10 moveable nodes on each part. You could even introduce a gravitation element so that strings and chains fall as they should.
• Updates to part snapping. I had the most trouble with parts that had holes and I needed things to line up. A shortcut could be introduced to activate "advanced" snapping mode, where each part would have even more snapping nodes, just so that it doesn't get in the way of builds that should remain simple.
• A "parts bucket". Basically, this would be a way that you could select all the pieces you need, to include colors right away, and put them in sort of a tab, that could later be selected and placed. This would be extremely helpfully in finding out what pieces still need to be modeled before publishing. If you had instructions for a set, you would go through and place them in your bucket, find what you're missing, model them, etc... Your bucket is saved when you exit the workshop, so that you can add parts to it. This may also be a good place to be able to pull the parts listing from. It may take some load off the code that extracts that data.
• Orthographic, non-projected view option. When clicking on front, back, right side, etc... it give you a perspective view depending on where center is. A non projected view would be great.
• An official parts/colors section, maybe a tab
• All other/custom parts/colors section, maybe a tab
• A click and drag/snap feature, like LDD
• Addition of "specific to color" part numbers on parts list
• A PDF download option. This could include instructions, but mainly because who uses CSV 😃 unless you code. User friendly would be nice though.