Create a Table from existing columns

Hi arcejames ,

if you're looking for a dynamic solution, you can use this approach:

// Query1
let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUYoA4oKcxOKSzGQgyxCIk/PLUouAdCIQl1QWpBoqxepgU2sEks8vAJJJUJVGYJVOQF4kEOemliTmAGljEDszJSUnFcgAIZiiKCAuKk1KAtuGQLGxAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Type = _t, Material1 = _t, Description1 = _t, Materia2 = _t, Description2 = _t, Material3 = _t, Description3 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Type", type text}, {"Material1", type text}, {"Description1", type text}, {"Materia2", Int64.Type}, {"Description2", type text}, {"Material3", type text}, {"Description3", type text}}),
    SplitToColumns = List.Skip(Table.ToColumns(#"Changed Type")),
    Materials = List.Union(List.Alternate(SplitToColumns,1,1,1)),
    Descriptions = List.Union(List.Alternate(SplitToColumns,1,1)),
    NoOfColumnStacks = (Table.ColumnCount(Source) - 1 ) / 2,
    CreateTable = Table.FromColumns({List.Repeat(Source[Type], NoOfColumnStacks), Materials, Descriptions}),
    ReplaceBlankByNull = Table.ReplaceValue(CreateTable,"",null,Replacer.ReplaceValue,{"Column2", "Column3"}),
    FilterOutNulls = Table.SelectRows(ReplaceBlankByNull, each ([Column2] <> null) and ([Column3] <> null))
in
    FilterOutNulls

It also allocates the Types from the first column to the other rows - hope that's OK.
It is a variation of the approach I've publishd here, if you're interested in how it works: https://www.thebiccountant.com/2019/02/28/unstacking-columns-in-power-bi-power-query-excel/ 

a slightly different solution  to stack the columns, based (actually, doing the reverse) on ImkeF  suggestions at

https://www.thebiccountant.com/2019/02/28/unstacking-columns-in-power-bi-power-query-excel/ 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUaoA4oKCAiBpCMTJyclAMhGISwyVYnXQlRiBJEpKgGQSiGUEVuIEZFYCcW5uLpA0BrEyU4AkCMHkq4C4qKgIKgqViwUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"type" = _t, m1 = _t, d1 = _t, m2 = _t, d2 = _t, m3 = _t, d3 = _t]),
    ct = Table.TransformColumnTypes(Source,{{"type", type text}, {"m1", type text}, {"d1", type text}, {"m2", Int64.Type}, {"d2", type text}, {"m3", type text}, {"d3", type text}}),
ttc=Table.ToColumns(ct),
cols=Table.ColumnNames(ct),
stack=(SCgrpCols)=> List.Combine(Table.ToColumns(Table.SelectColumns(ct,List.Select(cols, each Text.StartsWith(_,SCgrpCols)))))

in   
Table.FromColumns({ttc{0},stack("m"),stack("d")},{"type","m","d"})

after a bit of makeup (after mash up)

let
    #"Query1 (2)" = let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUaoA4oKCAiBpCMTJyclAMhGISwyVYnXQlRiBJEpKgGQSiGUEVuIEZFYCcW5uLpA0BrEyU4AkCMHkq4C4qKgIKgqViwUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"type" = _t, m1 = _t, d1 = _t, m2 = _t, d2 = _t, m3 = _t, d3 = _t]),
    ct = Table.TransformColumnTypes(Source,{{"type", type text}, {"m1", type text}, {"d1", type text}, {"m2", Int64.Type}, {"d2", type text}, {"m3", type text}, {"d3", type text}}),
ttc=Table.ToColumns(ct),
cols=Table.ColumnNames(ct),
stack=(grpCols)=> List.Combine(Table.ToColumns(Table.SelectColumns(ct,List.Select(cols, each Text.StartsWith(_,grpCols)))))

in   
Table.FromColumns({List.Combine(List.Repeat({ttc{0}},3)),stack("m"),stack("d")},{"type","m","d"}),
    #"Removed Blank Rows" = Table.SelectRows(#"Query1 (2)", each not List.IsEmpty(List.RemoveMatchingItems(Record.FieldValues(_[[m],[d]]), {"", null})))
in
    #"Removed Blank Rows"