private readonly Dictionary<string, BlockingCollection<ProductModel>> _cache;

for (var i = 0; i < _numberOfInstancesPerCollection; i++)
{
    //this collection is the TValue of the _cache
    productModelCollection.Add(new ProductModel(name, version, ProductModel.CreateFromVT(....)));
}

for (var i = 0; i < _numberOfInstancesPerCollection; i++)
{
    //instance folder creation
    string instanceFolder = string.Format(.... i + 1);
    Directory.CreateDirectory(instanceFolder);

    //package resource files is created on disk
    foreach (Package package in packageList)
    {
        string localFilePathPerInstance = string.Format("{0}\{1}", instanceFolder, package.Filename);
        File.WriteAllBytes(localFilePathPerInstance, package.Data);
    }

    //create a product model from the actual package filename and add it to the cached collection
    productModelCollection.Add(new ProductModel(...., ProductModel.CreateFromVT(...., instanceFolder, vtzPackage.Filename)));
}

//instance folder creation
string instanceFolder = string.Format(....);
Directory.CreateDirectory(instanceFolder);

    //package resource files is created on disk
foreach (Package package in packageList)
{
    string localFilePathPerInstance = string.Format("{0}\{1}", instanceFolder, package.Filename);
    File.WriteAllBytes(localFilePathPerInstance, package.Data);
}

for (var i = 0; i < _numberOfInstancesPerCollection; i++)
{
    //create a product model from the actual package filename and add it to the cached collection
    productModelCollection.Add(new ProductModel(...., ProductModel.CreateFromVT(...., instanceFolder, vtzPackage.Filename)));
}