How to make excel diagrams in multiple dimensions?

You have not given much detail regarding what you want to do, but, being the optimist that I am, I expect that, yes, it is possible.

I often find that these questions often turn out to be more about how you arrange the data in the spreadsheet. There are 2 "built in" charts for showing data in 3 dimensions: bubble charts and surface/contour charts. They each use data arranged differently.
Bubble charts: https://support.office.com/en-us/art...rs=en-US&ad=US
Surface charts: https://support.office.com/en-US/Art...rs=en-US&ad=US

Based on the little information you have provided, I would suggest you start there. Study these examples (in particular how they have arranged the data in the spreadsheet), then see if you can arrange your data similarly in your spreadsheet for the chart type you decide you want to use.

I cannot make out what your plot is supposed to show. All I can see is a data marker for 2 of the "pens", with accompanying lines for each "user" and the length of those lines might be based on "spent" values. I notice that Tom has two entries for pen2 -- is the first step in this process going to be getting the spreadsheet to compute totals for each pen+user combination (SUMIFS() function maybe)??

When you say that every item has several dimensions (x,y,z), which column are considering x, y, and z?