I decided to create a script that simulates MakeJoints but uses constraints instead of old joints. It works well enough, but for some reason for my test cases it doesn't detect that any of the parts are touching. It works when I use it in the trowel tool, but it doesn't work for the old Arcade Machine model (look it up) or my custom test case. It simply doesn't detect that any of the parts are touching. My code: 

local module = {}
function module.JoinAdjacentConstraints(brick)
	for _, part in pairs(brick:GetTouchingParts()) do
		local weld = Instance.new("WeldConstraint")
		weld.Part0 = brick
		weld.Part1 = part
		weld.Parent = brick
	end
end
function module.GetSurface(position, object)
	local surfaces = {
		back = object.CFrame * CFrame.new(0, 0, object.Size.Z);
		front = object.CFrame * CFrame.new(0, 0, -object.Size.Z);
		top = object.CFrame * CFrame.new(0, object.Size.Y, 0);
		bottom = object.CFrame * CFrame.new(0, -object.Size.Y, 0);
		right = object.CFrame * CFrame.new(object.Size.X, 0, 0);
		left = object.CFrame * CFrame.new(-object.Size.X, 0, 0);
	}
	local surface = "back"
	for side, cframe in pairs (surfaces) do
		surface = ((position - cframe.p).magnitude > (position - surfaces[surface].p).magnitude and surface or side)
	end
	return surface
end
function module.TitleCase(str)
	local result=''
	for word in string.gmatch(str, "%S+") do          
		local first = string.sub(word,1,1)
		result = (result .. string.upper(first) ..
			string.lower(string.sub(word,2)) .. ' ')
	end    
	return result
end
function module.MakeJointsConstraints(brick)
	local opposites = {
		back = "front";
		front = "back";
		top = "bottom";
		bottom = "top";
		right = "left";
		left = "right";
	}
	local axis = {
		back = Vector3.new(0, 0, -1);
		front = Vector3.new(0, 0, 1);
		top = Vector3.new(0, 1, 0);
		bottom = Vector3.new(0, -1, 0);
		right = Vector3.new(1, 0, 0);
		left = Vector3.new(-1, 0, 0);
	}
	local axis2 = {
		back = "Z";
		front = "Z";
		top = "Y";
		bottom = "Y";
		right = "X";
		left = "X";
	}
	print(brick)
	for _, part in pairs(brick:GetTouchingParts()) do
		local surface = module.GetSurface(part.Position, brick)
		print(surface)
		if brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Glue or brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Weld or (((brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Studs or brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Universal) and (part[string.gsub(module.TitleCase(opposites[surface]) .. "Surface", "%s+", "")] == Enum.SurfaceType.Inlet or part[string.gsub(module.TitleCase(opposites[surface]) .. "Surface", "%s+", "")] == Enum.SurfaceType.Universal)) or ((brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Inlet or brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Universal) and (part[string.gsub(module.TitleCase(opposites[surface]) .. "Surface", "%s+", "")] == Enum.SurfaceType.Studs or part[string.gsub(module.TitleCase(opposites[surface]) .. "Surface", "%s+", "")] == Enum.SurfaceType.Universal))) then
				local weld = Instance.new("WeldConstraint")
				weld.Part0 = brick
				weld.Part1 = part
				weld.Parent = brick
			end
		if brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Hinge then
				local hinge = Instance.new("HingeConstraint")
				local attach0 = Instance.new("Attachment")
			attach0.Axis = axis[surface]
			attach0.Axis[axis2[surface]] = math.abs(attach0.Axis[axis2[surface]])
				attach0.Position = axis[surface] * brick.Size[axis2[surface]]
				attach0.Parent = brick
			local attach1 = Instance.new("Attachment")
			attach1.Axis = axis[opposites[surface]]
			attach1.Axis[axis2[surface]] = math.abs(attach0.Axis[axis2[surface]])
			attach1.Position = axis[opposites[surface]] * brick.Size[axis2[surface]]
				attach1.Parent = part
				hinge.Attachment0 = attach0
				hinge.Attachment1 = attach1
				hinge.Parent = brick
			end
		if brick[string.gsub(module.TitleCase(surface) .. "Surface", "%s+", "")] == Enum.SurfaceType.Motor or brick.BackSurface == Enum.SurfaceType.SteppingMotor then
			local hinge = Instance.new("HingeConstraint")
			local attach0 = Instance.new("Attachment")
			attach0.Axis = axis[surface]
			attach0.Axis[axis2[surface]] = math.abs(attach0.Axis[axis2[surface]])
			attach0.Position = axis[surface] * brick.Size[axis2[surface]]
			attach0.Parent = brick
			local attach1 = Instance.new("Attachment")
			attach1.Axis = axis[opposites[surface]]
			attach1.Axis[axis2[surface]] = math.abs(attach0.Axis[axis2[surface]])
			attach1.Position = axis[opposites[surface]] * brick.Size[axis2[surface]]
			attach1.Parent = part
			hinge.Attachment0 = attach0
			hinge.Attachment1 = attach1
			hinge.Parent = brick
				hinge.ActuatorType = Enum.ActuatorType.Motor
				hinge.AngularVelocity = 5.5
			end
	end
end
return module

My test case: https://www.mediafire.com/file/i4bs95r0rpr8pa7/testcase.rbxmx/file

Anonymous