What does a project cost sheet for an interior design project look like when including contingencies?

If it helps, below is the project cost element tables including the associated 3-point estimates, mean, and variances.

Cost element	Optimistic Cost	Most likely Cost	Pessimistic Cost	Mean	Standard Deviation	Variance
Material Cost	60	80	100	=(60+80+100)/3=80	=square root of (((60-80)^2)+((80-80)^2)+((100-80)^2))/2 =20	=20^2=400
Overhead Cost	50	60	94	=(50+60+94)/3=68	= square root of (((50-68)^2)+((60-68)^2)+((94-68)^2))/2 =23.065	=23.065^2=531.994
Labor Cost	80	120	140	=(80+120+140)/3=113.33	=square root of (((80-113.33)^2)+((120-113.33)^2)+((140-113.33)^2))/2 =30.55	=30.55^2=933.3025
Rental Cost	70	110	130	=(70+110+130)/3=103.33	=square root of (((70-103.33)^2)+((110-103.33)^2)+((130-103.33)^2))/2 =30.55	=30.55^2=933.3025