Can't seem to get parts to weld together ?

Hi, everytime i generate a part with this script, it doesnt weld that piece to any other object.

The primary focus of this code is the elseif statement. That's where all the welding happens.

Thanks for the help.

local Tool = script.Parent
xSize = 3
ySize = 1
zSize = 5
Mouse = game.Players.LocalPlayer:GetMouse()
newBlock = nil
local Model = Instance.new("Model",workspace)

function createSingleInstance()
--	print(Mouse.Target)
--	print(type(Mouse.Target))
	if Mouse.Target.Name == "Baseplate" then
	
		local groundBlock = Instance.new("Part",workspace.Model)
		groundBlock.Name = "Block"
		groundBlock.Anchored = true
		groundBlock.Size = Vector3.new(xSize,ySize,zSize)
		groundBlock.Material = Enum.Material.Plastic
		groundBlock.Transparency = 1
		groundBlock.Position = Mouse.Hit.p
		
		groundBlock.BackSurface = Enum.SurfaceType.Smooth
		groundBlock.BottomSurface = Enum.SurfaceType.Smooth  
		groundBlock.FrontSurface = Enum.SurfaceType.Smooth    
		groundBlock.LeftSurface = Enum.SurfaceType.Smooth    
		groundBlock.RightSurface = Enum.SurfaceType.Smooth 
		groundBlock.TopSurface = Enum.SurfaceType.Smooth 

		groundBlock.Transparency = .9
		wait (.01)
		groundBlock.Transparency = .8
		wait (.01)
		groundBlock.Transparency = .7
		wait (.01)
		groundBlock.Transparency = .6
		wait (.01)
		groundBlock.Transparency = .5
		wait (.01)
		groundBlock.Transparency = .4
		wait (.01)
		groundBlock.Transparency = .3
		wait (.01)
		groundBlock.Transparency = .2
		wait (.01)
		groundBlock.Transparency = .1
		wait (.01)
		groundBlock.Transparency = 0

	elseif Mouse.Target.Name == "Block" then
	
		local newBlock = Instance.new("Part",workspace.Model)
		local target = Mouse.Target
		newBlock.Name = "Block"
		newBlock.Anchored = true
		newBlock.Size = Vector3.new(3,3,3)
		newBlock.Transparency = 1
		newBlock.Position = Mouse.Hit.p -- nearest surface?
		
		newBlock.BackSurface = Enum.SurfaceType.Weld  
		newBlock.BottomSurface = Enum.SurfaceType.Weld  
		newBlock.FrontSurface = Enum.SurfaceType.Weld  
		newBlock.LeftSurface = Enum.SurfaceType.Weld  
		newBlock.RightSurface = Enum.SurfaceType.Weld
		newBlock.TopSurface = Enum.SurfaceType.Weld
		
		--newBlock.CFrame = otherBlock.CFrame * CFrame.new(0, newBlock.Size.Y / 2 + otherBlock.Size.Y / 2, 0)
		

		workspace.Model:MakeJoints()
		newBlock.Anchored = false
		
		newBlock.Transparency = .9
		wait (.01)
		newBlock.Transparency = .8
		wait (.01)
		newBlock.Transparency = .7
		wait (.01)
		newBlock.Transparency = .6
		wait (.01)
		newBlock.Transparency = .5
		wait (.01)
		newBlock.Transparency = .4
		wait (.01)
		newBlock.Transparency = .3
		wait (.01)
		newBlock.Transparency = .2
		wait (.01)
		newBlock.Transparency = .1
		wait (.01)
		newBlock.Transparency = 0
				
	end


end

Tool.Activated:Connect(createSingleInstance)

What it looks like in game: https://imgur.com/a/6tYFihh

Use a weld plugin. They are free and weld things together without silly scripts. Hope this helped! Link: https://www.roblox.com/library/148570182/Weld-Plugin/