Add a "z" axis to an existing graph and make it 3d

Question

I have a data frame as following:

z<-data()

      cost time Period Type
    1    72   51     10    1
    2    68   60     10    1
    3    79   43     10    1
    4    67   79     10    1
    5    79   67     10    1
    6    89   35     10    1
    7    80   34     10    1
    8    78   45     10    1
    9    76   47     10    1
    10   69   57     10    1
    11   67   56     10    1
    12   69   45     10    1
    13   79   57     10    1
    14   70   56     10    1
    15   80   56     10    1
    16   89   56     10    1
    17    3    5      1    0
    18    5    8      2    0
    19   89   67      3    0
    20   46   56      4    0
    21   23   34      5    0

I draw mahalanobis distance between the project type 0 and project type 1 as following.

  x<-z[,c(1,2)]
require(robustbase)
  x.mcd=covMcd(x)
   title(main="Distance from benchmark space", col.main="red", font.main=4)

  drawMahal(x,center=x.mcd$center,covariance=x.mcd$cov,quantile = c(0.975, 0.75, 0.5, 0.25,0.01) ,m =1000,lwdcrit =2 ,col=ifelse(x1$Type==1,"green","blue"),pch=2,col.axis="blue",frame.plot=TRUE,cex=2)
  legend("top",pch=c(2,2),col=c("green","blue"),c("Current","Benchmark"),bty="o",box.col="darkgreen",cex=.8)
  axis(1, col = "blue",col.axis = "blue",  lwd = 0.5,tck=1,col.ticks="light gray")
  axis(2, col = "blue", col.axis = "blue", lwd = 2,tck=1,col.ticks="light gray")

So the out put is like following:

Q1: How can I add an axis of period from dataframe z to the above graph to make the graph 3d shape.

Q2 add lines from blue points to the centroid of mahalanobis space? and add the line from the blue point of period 1 to 5 respectively with the different color.

I have used plot_ly and make it 3d but Still I could not draw ellipses around it.

f<-plot_ly(n,x=n$cost,y=n$time,z=n$Period,color = n$Type,type="scatter3d", mode="markers")

and the graph that I got it is as following: For the eliplipses I wrote the following codes, but it does not show anything.

z <- layout(f, title = 'Highlighting Regions with Circles', 
                                   shapes = list(
                                    list(type = 'circle',
                                 xref = 'x', x0 = min(f$cost), x1 = max(f$cost),
                        yref = 'y', y0 = min(f$time), y1 = max(f$time),zref='z',z0=1,z1=1,
                                    fillcolor = 'blue', line = list(color = 'red'),
                            opacity = 0.1)))